Hello,
On my Max2, I just replaced the Onyx battery with a new one (C11-ME370T for Google Asus Nexus 7 1st Generation Release 2012 as described in this thread). (23€ all included !)
Not very easy, but with care, I did it and it works !
The most difficult point is to remove the plastic sheet that covers the screws. With a knife (rounded end) I could do it with only a few scratches. Keep this sheet far from dust as you may put it later back in place without adding glue.
It's then easy to remove the screws (very small ones !) and open the Max2 to find the battery.
The Onyx battery is fitted with a small printed board that you must put on the new battery (with some wires due to the different dimensions), after you removed it's own printed board. Soldering is mandatory, taking care that you must not warm a Lithium battery. Take real care !!!
Note : on the new battery, there are 2 black wires that go into the battery : no problem, it's just a thermal sensor that is not needed. Pull the wires and the sensor comes, then detach the printed board from the battery : not needed.
Note 2 : in the attached file, the photo of the plastic sheet is not from me, but can be found in this thread.
After charging, the battery seems to work properly, as if the Max2 was new.
