You may be in luck (relatively speaking)...I just went through the whole metal handle replacement thing (for the third time except this time I use the metal lever), so my mind is a little fresh about what's in there.

These are the steps I would take in order.

1) with all the inner panels removed, along with the removal plates on the door, see if you can remove the cable that is connected to the latch handle you replaced. Long needle nose pliers might help. Use mirrors and flashlights if needed. Once you have the cable freed from the door handle lever...pull the ball at the end of the cable with a pair of pliers. The idea is that with the cable in your hand, you can pull on it to allow for further travel than the arm of the lever could do. That my free the lock mechanism.

2)If that fails (because the cable might be screwed up from the other end at the mechanism)...see if you can at least see where the cable connects to the lock mechanism. Can you see the gold colored plated arm the cable connects to? You must move that arm from the passenger side to the driver side direction (left to right if you are facing the rear of the car and can look out the back glass from inside).
I dont remember what it looks like enough to know if you have access.

What may have happened if moving the lock lever doesn't work is that the lock's sliding metal parts (look like a hook that wraps around the post anchored to the bumper area) may be jammed. The lock mechanism gets very dirty and grimmy. The sliding part that hooks and catches the post slides the way scissors slide...so think of a really rusty, pair of scissors and how it would be harder to move. Well the level is supposed to move that sliding hook. My lock was all grimmey and dirty...so I shot a bunch of brake cleaner and wd 40 in and around it. Well that just caused some kind of rubber spacers, in there, to swell and interfere with the 'scissor action' even more...making the lock stick sometimes for me. I bet that is your problem...so once you do get it open...you'll need a new one probably. I couldn't figure out how to restore mine. I'd rather live with it until I source a craigslist part out of a sequoia for one.

3) All else fails....remove the tow hitch ...then under the bumper...you can see the bottom where the two bolts that holds the anchor plate (I spoke of earlier) to the bumper area. The nuts look to be tack weldled...so you can't remove them unless you can undo the welds...but I would simple drill out the bolts. There is plenty of room to get an extended drill bit in there. Try to drill down the center of the bolts with a small bit first (like 1/16) then move to larger bits. If you keep it centered well....you can then simple tap a slightly larger thread and use new bolts to match. With the two bolts out...the door will swing open with the anchor plate attached....but then you can pry the "scissor hook" manually and then address accordingly.

Well...that's my .02 worth

 

Thanks Peculiar... I tried pulling the cable as you recommended in step one. No dice there.
Question for you - do you (or anyone reading this) know if you can remove the black cover off of the locking mechanism/actuator in the rear door? It would seem logical enough to have that exposed so I could manually release the door. The bolts on the bottom of the hatch go directly into this plastic locking mechanism and obviously i cant get to the bolts since the door wont open.

I also wonder if I can 'cut into' the black plastic cover on the lock/actuator and gain access to the locking mechanism that way?

I may attempt to spray some break free in there tonight and see if that helps loosen anything up.

Thanks for the input.
What a pain this is

 

If you can get enough access to cut the plastic housing...you probably could move the lever on the actuator. If so...jiggle it back and forth as you push out on the door. Try to cause vibration so that the "lock" can slip free. I don't think its easy to get inside of it, though. If it was...I would have noticed it when I had the actuator on the bench, never mind it being on the truck. I just recall thinking that it was a lot of work and buying a new one was better for me.

Also...def try spaying it with break free. I just looked at my truck..and you can def get the spray on to the area that is probably stuck. Based on what I know about how the actuator work and being able to see it on my truck with the door locked....I could get spray in there. You might want to bend the little red straw upward so that the spray can get to the sliders.

Try grabbing the bottom of the door from outside (you can curl your fingers under it...and have someone pull on the cable while you try to move the door in and out. Again...you're trying to create a little movement so that sliding part can slip free.

I would also try using dental picks (stuff you buy from Harbor Frieght ) to see if I could cause the "locking hook" to move. As I look at my truck...there is plenty of room under the door lip to get to it. If you need pics or video of me point it out more specifically...let me know. Technology is easy today for that kind of thing.

 

Wall09, I think I have the same problem as you.

Were you able to get the inside rear door panel off with the door closed without damaging anything?
If so where did you start?

 

I just recently had the same problem on my 2005 Sequoia (the hatch locked and cannot get it open). After removing the plastic panels and the one metal cover, I can see the cable and manual release working ok and cable ok on both ends. I concluded it was the actuator and ordered on (Standard Motor Products DLA197 - Amazon had these for about $80 including shipping). So, my problem was to get the door opened. In my case, it was of no use to disconnect the cable at the top (the manual latch handle). The cable was ok on both ends (I could hear and feel the cable doing its job inside the black plastic cover that encloses the lock and the actuator. The actuator was stuck in the locked position (while the actuator would make a small popping sound, it would not unlock the lock). I needed to get into the black plastic cover. There are two Phillips screws that are on the outside door side that holds the cover to the lock. I think if one could get these screws out, then the plastic cover would move upward enough to get a finger in there and move the lever on the actuator (put the lock in the unlock position and the cable will open it). I could not get the two screws out...not enough room for me. I wasn't about the get under the bumper and drill out the 3 bolts on the bumper. So, I decided to cut the black cover. I cut it on the door side (outside) along where the cable went through the cover. Side cutters (*****) and a razor knife worked ok. After splitting it, I bent it up and out of the way. You can now get a finger in there and move the lock and the actuator arm (seemed very simple once you can get in there. My door opened after moving the lever. Others have posted how to get the lock out once the door is open....I won't repeat here. Once you cut the cover, its pretty much destroyed. I assume the cover helps with keeping dirt and moisture away from the lock....it migh just bee for looks. The cover also has a rubber bushing that helps hold the cable for the lock. So, if your door is stuck locked and you have determined its the actuator, order the protective cover when you order the actuator. They are between $35 and $40. Its dry where I live and I'm leaving it open....it will be easy next time to unlock from the inside. Also, if I have to get in there again with door locked, I'm going to drill a hole in the cover near the actuator so I can unlock it without destroying the cover (will make a plug for the hole). It would have been very simple for Toyota to attached a 'lever' through an opening on the cover to instantly open the door.

Hope this helps.
RP

 

FYI: Ran into similar on 02 just bought 7/2106). I was fortunate, nothing broken & got door open by pulling cable.
the cable was stretched and slipped out of notch for steel part of cable, & also cable end ball retainer arm.

l tried cutting small stub(1- 1.25 inch) of 3/8 tubing & slidg it over actual plastic lever to increase travel when door release handle outside was pulled. That didn't wk.
Scouring my gar. for a 1/4 hard plastic tubing I could slice down the side, & then slide over cable at the very end ball to attain addit. tension....No luck

I did come across one of the blue plastic clasp wire splices. These are ones that snap open & close & you can put 2 wires in one side & one in from other. BINGO.
I opened -removed small aluminum crimp inside & slid it over very end of cable so it was positioned by ball. Then insert cable into position & other end of blue splice rested on plastic assembly ball normally rested in. It worked but door would barely latch so I removed splice & got hacksaw & cut 1/8 in. off end of splice, WHALAA. ....Works like a charm

Hopg saves someone from replacing whole cable/ lock actuator assembly.