Macbook Air (2017) stuck in restart loop after log-in

hi, i‘m having this problem: to start off i’m not using my macbook regularly and it had a weak battery for a while (it usually dies a few min after using, but on the few occasions i’m using it i just leave it plugged). today i forgot to plug it in which resulted in it shutting down. after restart the login screen appeared, but after logging in, the loading bar moves for 1 sec and the screen turns black. after another few seconds a different black screen appears saying “your computer restarted because of a problem”. pressing any key returns me to the login screen and it starts all over again. i started restarting in recovery mode to reinstall macos but it says that my volume is locked. is there any way i can fix this without losing my data. ps: i’ve seen a reddit post saying it might be a battery indicator problem…regarding this i’ve noticed that even though my magsafe charger indicates green light (100% right?) the battery level on the login screen only shows 97%. i’d be so thankful if somebody could help me out!! thanks in advance!!