2012 Plug-in Multiple Errors on MFD

I have a 2012 Prius Plug-in with about 250k miles on it now. I recently (several months back) did a head gasket replacement due to cylinder 1 misfire and symptoms pointed to a blown gasket.

Car was fine for few months and I randomly started having issues. First is the "Refuel Ready" sign will flash for less than a second while driving, along with "Fuel Door Opening" message as well. They both flash intermittently but very very briefly. This was the beginning for a whole host of new issues.

Since a fuel door issue isn't a high priority, I kept driving and recently, I will randomly get "Check PCS System", "Check Hybrid System", and "P-Lock Malfunction" messages as well. One time, before the head gasket replacement, I received a "U0100" error which was "Lost Communication With ECM/PCM".

All (if not most) of these errors seem to be related since all the errors will go away at the same time or come back at the same time. I can get the error while driving on the freeway and by the time I exit the freeway, the errors can go away. In severe cases, I will get the error and it won't let me turn off my car due to the P Lock Malfunction.

My guess is either a damaged wiring harness (possibly from when I did the head gasket?) or a faulty ECM based on the U0100 error. I'm wondering if Techstream will be able to read what's going on or if there's a good method to diagnosing this problem.

Edit: I just changed my 12v battery yesterday (8/12/2023) with a battery from the Toyota Dealer to rule out a faulty 12v battery. Also, all errors will go away and will be perfect after removing 12v battery till the error returns randomly.