I seen a couple posts indicating people have done it themselves. What vendor did you purchase batteries from? Any words of wisdom/warning?
I bought mine from Topcon though I believe much cheaper ones are available now -- haven't tried them.
My advice is: take your time and be gentle -- it's not a complicated job but if you're not careful you can strip the threads on the screws and/or the housing or, MUCH worse, fry the battery. Be ABSOLUTELY sure that the wires, which are tiny, are free and not about to get squeezed before you re-tighten the screws -- if they get pinched tight they will short out and fry the battery irreversibly. Also, be gentle with the rubber gasket that goes around the front plate or you could tear or otherwise damage it. Make sure it's seated properly before you tighten the screws. Then check those wires again!
Worth repeating:
Be ABSOLUTELY sure that the wires, which are tiny, are free and not about to get squeezed before you re-tighten the screws -- if they get pinched tight they will short out and fry the battery irreversibly