TUSA computer woes

I just got an older TUSA Imprex II computer when I bought some gear. The
battery seems weak and the indicator shows same.

The manual from the TUSA website says I can replace their battery, but on
the back it says "Do not remove screws" Two are plain and two are sealed
with red lacquer. I removed the two plain screws, but the back did not come
off.

Calls to local shops (South Florida) get me nowhere, as they want to sell
the good stuff and I'm on a tight budget. Heck. I would have paid to have
them help me.

The computer is made by Suunto, so it's probably OK.

Any ideas out there about removing the sealed screws? I just want to
replace the battery.

Thanks,

Jack