Nokia N95 Mod [portable] Site
Remove the battery cage. Solder a 2-pin JST connector to the motherboard. Attach a 3.7V 3500mAh drone battery (size 603040). Use double-sided tape to stick it to the back cover.
In 2007, the Nokia N95 was a beast. It was nicknamed the "Multimedia Computer" for a reason: a 5-megapixel Carl Zeiss lens, GPS, Wi-Fi, a sliding two-way keypad, and a Symbian S60v3 operating system. It cost more than a laptop. nokia n95 mod
Only three people in the world have done this successfully. Search for "N95 Cyberdeck" on TinkerSpace forums. The N95's 3.5mm jack is soldered weakly to the board. After a decade, it wobbles. Remove the battery cage