NFC Antenna. You should carefully transplant it to new battery, in case your new battery is without one (what is the case for most 3rd party batteries available)

For anyone following this guide, please avoid Eneloop AAAs.

I was initially happy and added a comment on 11/7/2019. Batteries didn’t perform very well, but I though they have to “break-in” by couple of (dis)charges. Now the battery time is similar. After about 3 minutes, motor rpm falls drastically and about at 10 minutes mark the trimmer stops completely.

I do not know, whether something else is faulty, but I suspect the batteries.

Thanks for this awesome guide! Disassembled without breaking anything. It was little harder to find batteries with tabs, but they are already being shipped to my door :) I am looking forward to breathing new life to this otherwise awesome trimmer. Lately it wasn’t even able to complete my heavy stubble trim, what takes around 5 minutes.