crwdns2934241:0crwdne2934241:0 mayer

crwdns2934249:0crwdne2934249:0:

3.6 volt 1/2 AA PRAM battery.

You can see it on step#13 of this guide.  Look for the purple and black small battery:

[guide|54877]

crwdns2915684:0crwdne2915684:0:

open