Phone restarts when lightly hit or bumped

Hey there, as the question states, my S8+ restarts whenever it is lightly hit or bumped; it’ll even happen sometimes when it’s swinging around in my pocket.

Background/Context:

I have dropped the phone MANY times and I’m not sure if that may have affected the adhesive on the battery or the connector. I was about to buy the iOpener kit but am not sure what the possible cause may be, don’t want to go in blind. Best guess is a loose battery connector after reading the battery replacement guide.

Would love some help on this! Previously had the front glass replaced, but I’m pretty sure this wouldn’t have affected it.