If you are the original owner, on the new RC log enter your old email used on the previous RC then select reset password. This should allow you create a new password and use the drone IF you are the original owner.
There is one way. If you have care refresh just damage the drone and send it back for a replacement which will come with a much older version of FW, then just update till 0600. ;)
Here you go but need to use Drone Hacks app in Windows to downgrade it.
https://www.dankdronedownloader.com/DDD2/app/index.php?Brand=DJI&model=wm261&ver=01.01.0600&type=Aircraft
Just get yourself a Dji 100W charger. It's not expensive and be on the safe side. Will also work if you upgrade drones. I have had mine since I got the Mavic 3 OG