In my opinion this is one of the best computers ever produced for basic recreational diving, it was rebranded by so many manufacturers that I forget now, super reliable, long battery life, easy to read and understand - you dont need a manual dive with it once and you will know everything there is - keep it, it will serve you well for a long, long, time to come.
Those units have an easily changeable battery as you now obviously have found out and only weak point on the computer was where the straps attach to the module via a long SS pin, with the strap movement and age the strap can and often do's perish along the join, keep an eye there so you dont lose the unit, but other than that - great, great little computer.