Wilton S331A Problem

[Boofrmb]

Hi all.
Just seeing if there is anyone out there that would be able to assist me with my Wiltron Site Master.
Having an issue with it  and not sure if I need to send it away for repair, or even if it's worth it.
It's a S331A.
It has a battery pack that started to leak, so removed it, and built a new one.
All good, then after a while, when turned on, it say firmware fails in self test. Now when I turn it on, still firmware fail, but have to reset contrast, and sweep speed appears to be very very slow, like takes minutes to do a cal.
Cheers
Robert