I have a Tiny4412, its was without battery a few month. Now, I put a new battery, but the hardware clock don't work.

# hwclock -s
hwclock: RTC_RD_TIME: Invalid argument

When I installd Android, the clock work fine. I installed Linux / UbuntuCore, the clock goes to 12-31-1969 21:00 and I can't update. Returns error.

How can I fix it?