boot loop & heat sink hot to touch

I have a macbook pro 15” mid 2015 that I changed the battery and trackpad w/flex cable…all worked well for a couple weeks until it suffered a low drop (18” - 24” on wood laminate floor). It suffered no physical damage that I can see, but it went into boot loop upon startup. I noticed that the heatsink or CPU gets too hot to touch. Pretty sure motherboard/logic board needs to be replace because the a short in the CPU.

Question #1…Am I way off base here with my diagnosis?

Question #2…If I replace the motherboard / logic board…are there any steps needed to take after install for it to work properly or just install, turn on and it works?