left joy con joystick going down when pressing up.

Hi! so im having an issue with my switch where if i hold up on the joystick with any level of force it will start teleporting between fully up and fully down really fast. this started happening after i "dropped it while i was asleep"... or thats what i told my parents anyway in actually smash bros got me salty and i missed the bed (threw it) lol. i ended up deciding to take it as a learning oppertunity and decided to grab a repair kit from amazon and see what i could do. once it arrived tho i replaced my joystick with both of the replacements in the kit and everysingle time the same problem persisted, it would always flash between up and down when holding up with force. after many calibrations and factory setting restores i eventually factory reset the whole switch and still the problem persisted.

for me this rules out 2 things. 1 : it cant be the joystick because it was happening on all 3. 2 : it cant be software because god knows i did everything i could with the software and the problem persisted.

the only thing i can think that it might be now is possibly a motherboard malfunction?

if anyone has some words of wisdom please let me know as i cant find anything else about this online