(supposedly) random shutdown issue

A fellow student spilled something the keyboard of his MacBook Air (13" Early 2015) a couple of months ago.

The keyboard was sticky and he got tired of using a bluetooth keyboard so he had me replaced the keyboard couple of weeks ago.

Anyway, while I was away, he came by and gave his laptop to my roommate (and she gave it to me, obviously!)

He said that the laptop would randomly shutdown and would show the flashing folder when turned back on.

In fact, he said it was having the flashing folder right when he gave it to her.

When I got back, and turn on the laptop, it functions normally. I turn it on and off multiple times, run diagnostics,etc. and found no issue.

I also want to point out there when was replacing the keyboard, I found sticky residue on the keyboard and keyboard backlight, but did not find any underneath the keyboard backlight.