Mastering gone fanuc robot

You should have a program with all zero pos? then remaster? if not you will have to remaster it and touch up points I'm guessing

You lost mastering completelly, there is no way to go back.

You will need to master each axis manually again aligning the zero marks.

Expect a loss in accuracy on that robot from now on, this probably will not be a problem if you are running a handling, spot/arc ot glue application, since robot will repeat the path even with an incorrect calibration, but you may have problems if your robot uses vision or you use a lot of tool offsets or frame offsets (linear movements will not work perfectly if calibration is very bad), you may also have problems with positions that were near a config change or turn number change, so you need to test every trajectory.

You will need to reteach all frames, check your utools and maybe modify points from the path... the only way to "restore" the calibration would be if you had the robot with all axis at 0 degrees when you switched the battery with robot powered off, but even that way, a new master count will be generated, and calibration will still not be as good as from factory.

In the future, make sure to always change battery with robot robot powered, so the encoderas don't lose the pulse counts. Also take note of the new master count and ref count values and write them on a sticker, put the new values inside the cabinet for future reference as the ones provided by the commisioning papers will not be valid.

Your master counts are now junk. You will have to remaster. If the robot was in a known position (home, maintenance, etc.) when you did this you could do a remaster at that position. You can pull that position from a backup. Otherwise you will have to jog the robot to its zero position and preform a remaster.