Autohelm hand bearing compass - instructions?

[sailorman]

Best thing they ever made.
I use mine constantly.
Just be careful with battery life, with heavy use its only about 6-7 years

One on fleabay at 99 squids

 

[huib]

good afternoon, after the winterstore, my autohelm HB doesn't work anymore: no display. new batteries don't help.
Is there anything I can do. The case seems to be "closed forever"?