2010 Dodge Caliber and my hatch is locked,will not open.I heard that if you remove the circular plastic piece from the panel you can trip the hatch open.Is that true and if so how would you trip it?

Searched on YouTube

when you go inside the trunk and remove round plastic piece,use a flaslight with a fiber optic light long enough to see inside the gate and the latch,you will see a white plastic thing,lifting it up or down will unlock the latch.if you can have someone pushing the gate outside to remove the pressure on the latch.

Does this open by using the key fob, or with the key?
if it opens with the key fob , then its possibly the lock/unlock actuator in the hatch behind the trim panel, or possibly a corroded wite

Although the liftgate has no inside release mechanism,
the liftgate trim panel includes an opening with a
snap-in cap that provides access to release the latch in
the event of an electrical system malfunction.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Although the liftgate has no inside release mechanism,
the liftgate trim panel includes an opening with a
snap-in cap that provides access to release the latch in
the event of an electrical system malfunction.

It is possible that the handle is stuck in the "open position" which will not allow the hatch to unlock.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Bad lock actuator: (NOTE: If your hatch is locked)
First remove rear panel- pull the plastic panel at the top center, until (2)clips pop off, then pop (2) more clips at the mid-center. Stick your arm down until you reach the lock, with your fingers, feel for the squishy plastic( inside is the bar that goes up to unlock), it is attached to the lever to unlock. Pull up the lever until you can open the hatch. There are four more clips at the top sides and middle sides, and four plastic screws at the bottom which is only accessible when the hatch is opened.
The lock is only sold as an assembly at $100.
Part Number #9L8Z-7843150 B

There is no lever or any key hole it is a fully electric operated power latch. As to the cause the park brake must be engaged and the car in park gear position before the hatch will open, is it?

I had the same problem with my 2001 Blazer. Just remove the panel by the screws located on the side of the tailgate, the problem was a bad actuator which pulls the lever to open the glass hatch. Once you take off the panel, remove the metal shield on the tailgate and the actuator will be mounted on the back of it. There are several ways to open the hatch on blazers and jimmys. You can try to release by inserting a small screwdriver and pushing left using the entry hole in the rear hatch deck just below the plastic trim in the center. This works ok unless the latch is out of alignment. The quicker way to release the window lock is to pull the center of the plastic trim (where it rises) toward the inside of the car and break the plastic trim attachment. Remember first to remove the hatch handle.By pulling away from the window, you can then insert a finger between the two walls of the lock assembly and push down. The window will open immediately. Ignore the broken trim attachment as there is plenty of support for the top of the door trim piece. Unbolt the 9/32 panel screws and the two phillips head side screws and the panel will come off. Careful of the rods clipped to the panel. They come off easily as does the hatch door activator. Rather than have to buy an actuator because the blue piece of plastic broke, replacements are available at online auto supply stores. Remember to make sure that the lever of the actuator hits the window release mechanism squarly. A little bending with pliers will align these two pieces so they strike evenly.

I dont know the exact method on this car but on most cars if you open the boot/ trunk it has little compartments near the lights on the inside of the car, if you pop those open you gan get to the bulbs and probly un screw the light unit it self. sorry if its no help.

Look inside the rear hatch area near the very rear of the vehicle. You should find a removable panel near the brake light housing. After you carefully remove the panel, look for some plastic wingnuts that hold the light housing in, and remove them, you should not need any tools to do this. After the nuts are removed you should be able to gently remove the tail light assembly from the rear of the car. Becareful not to damage the wiring. Now look at the back side of the tail lamp assembly and look for a locking tab on the light socket. Depress the locking tab and twist the light socket about a quarter turn, then pull the light socket away from the light housing. Pull the bulb out and replace it. Then reassemble and your done.