Worked entirely fine for me. Since I bought replacement sliders/feet as well, I just skipped the warming up steps. The glue still separated very easily and overall took me like 10 seconds to remove all feet
Regarding the battery/flex-cable step, I personally removed the flex cable first as it’s much more fragile and less replaceable than the battery cable
I also removed the logic board to clean the area below, it’s pretty straight-forward. The only thing one has to remember is where the on/off switch colors go again during re-assembly. Answer: the blue side is at the bottom (when the PRO Wireless label is readable and NOT upside-down), you can find a photo in step 10
The symptoms I had before the repair were a bit weird, which is why I initially wasn’t sure if it’s the battery or not. Basically, my mouse wouldn’t charge a lot, but also wouldn’t work for a long time while connected via cable. Both of these appear to be fixed now (I’ll try to remember to update this comment if it turns out to be broken)
For a replacement battery, I managed to find an original battery on eBay that was disassembled from a returned mouse. That way I could be sure I’m not going to receive some potentially dangerous knock-off version, which I didn’t want to risk.