Overwrite /system/bin/su using adb Can't overwrite su file in /system/bin/ my stupid classmate put a prank on me and inserted a different su binary coming from his linux pc instead of the already existing su in /system/xbin/

I want to overwrite it myself since even him can't do it

here's the adb shell su return:


  /system/bin/su: not executable: magic 7F45


Is there a way to replace this one with the already existing su in /system/xbin/? I've been trying to chmod the su overwritten su file for 3 months now.. I can't even chown cause IDK what are the users and IDK how to list all of them. Help. Thanks in advance.

P.S.

-can't load custom rom since I'm still on the way of rooting phone

-can't load stock rom for I'm using a very rare tablet (Arc Mobile 727M) can't find a good alternative for stock rom
Andrew, if su binary in xbin is proper, then run,

adb shell
/system/xbin/su -c mv /system/bin/su /system/bin/su-dead


then reboot and open terminal emulator and run su.

Did this device come pre-rooted? If not then what prevents you
from repeating the process you used to root?