I have Toy story 3 Geo trax remote, My granddaughter loves it. All of a sudden stopped working. I replaced all the batteris in remote and train. Red light is on and Remote is making all the sounds but the train doesn't run. I have tried hitting the side of the train, I have tried holding the forward position and pushing the train on my pants and rubber mat, nothing. Is there anything else I can do. Just bought it in april.

SOURCE: how do i operate the fisher price geo trax toys i

You're supposed to have a remote control that will send commands to make the train go.

SOURCE: I have a geotrax train that is not responding to

I had the same problem with two of our three engines. I read somewhere that you can get them running by hitting the side of the engine against a hard surface. I can't believe it... IT WORKED! I guess the motor gets **** and hitting it will get it going. All three engines are working now.

SOURCE: GEOTRAX REMOTES ARE NOTE COMMUNICATING

I had the same problem with two of our three engines. I read somewhere that you can get them running by hitting the side of the engine against a hard surface. I can't believe it... IT WORKED! I guess the motor gets stuck and hitting it will get it going. All three engines are working now.

SOURCE: I replace the batteries in the remote control and

According to the Instruction Manual it requires 6 AAA batteries, you will need a Phillips screwdriver to access the panel where you must replace it.
The remote controller and the engine need batteries.
Engine
• Locate the battery compartment on the back of the Engine. • Loosen the screws in the battery compartment door with a Phillips screwdriver. Lower the battery compartment door and insert three "AAA" (LR03) alkaline batteries. • Close the battery compartment door and tighten the screws with a Phillips screwdriver. Do not over-tighten. • If this product begins to operate erratically, you may need to reset the electronics. Remove the batteries and replace them in the toy.

SOURCE: Where do the bAtteries go

Here's the instruction manual: http://service.mattel.com/instruction_sheets/R2436-0920.pdf
It's difficult to tell without seeing it in-person but it appears to be on the main unit, probably on the bottom. Look for the battery cover which will have a phillips head screw. You'll need a screwdriver to remove it and insert the batteries as specified in the instructions.