iPhone recovery mode bootloop

so yesterday i reset my old iPhone 8 and all was ok i set it up and apps were downloading so before i slept i powered it off but today early in the morning i wanted to bring my old iPhone to my school but i saw it was already turned on and it was lagging as crazy nothing opened everything crashed and my side button randomly stopped working so i asked Siri to restart the device and it showed the recovery mode i tried restarting but it came back to recovery mode so after i came back from school i opened iTunes and erased the iPhone again thinking everything will be ok but after it reset (it erased liked normal) but after it reset it came back to recovery mode so i got confused and erased it again cuz i thought its a glitch but the same thing happened i hope there's a way to fix it because i dint turn on "backup iCloud photos" (and i think my side button is still not working)

[Re-Titled by Moderator]