my 2 cents; Worth it to see if you have valid signals at both the main ROM and at each of the installed rams but most importantly the "top 8k". meaning the 8K RAM that is closest to the system socket.
if there happens to be a cracked track on the PCB, that affects the memory subsystem, you will get this kind of behaviour. It would be reasonable for the CPU to end up in a loop under this sort of condition as well. Yes, I have seen this happen on my fleet of laptops. Not common in general, but more common on T102 and T200 for some reason.
