Q: Transmission

I've a 2011 Chevy Equinox w/ about 67400 miles on it. The CEL comes on randomly if I use the remote car starter or if it has rained. If I put the truck in gear like Reverse or Drive, the R or D will blink on and off and I cannot accelerate. I have to turn it off and on several times to get the blinking to stop. I took it to be looked at and one of the mechanics at the local shop I use, said that it looked like the computer just needed to be reset, he reset the system and it worked fine for a while and then it started happening again. The truck wont give my any issues for weeks and then while driving or even just starting it up, the CEL will come one it wont accelerate & the issues start over again. I'm being told by the owner of the local shop that the Transmission Control Module is faulty and that I need a new TCM and new transmission which will be $4200. Another mechanic said based on the description of the problem, it's either electrical or the computer system. Not sure what's true.

My car has 67400 miles.
My car has an automatic transmission.