If you search this forum, this topic will come up many times.
The problem is that we do not know what is inside your electrical cabinet. It could be an original mother board with a NiCad battery soldered in, or a coil style lithium on a newer board, or a Dallas Real Time Clock chip as mentioned before.
post a picture of the control part of yor electrical caand we may be able to help you.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)