At least when I bought it, my pine64 had a real slow and buggy O.S. Also it was draining the battery badly. I switched it to Ubuntu Touch, but it was using my SD card.
After 1 hour of research, I was able to fix this flashing it from the EMMC memory (internal).
- 1 SD card (32gb in my case)
- 1 Pine64 phone
- 1 Laptop with SD card port
- 1 USB-A to USB-C cable
2.-Stick your SD in your phone and turn it on to see Jump Drive
3.- Download the ubuntu-touch-pinephone.img.xz image
4.- flash it to your phone in the EMMC memory via USB using Balena Etcher.
5.- Restart your phone when your installation has ended.
Bonus: Remove the SD card and format it from your Laptop / PC, put it back in your mobile to get more room now.
Sadly, even after changing the operative system… the phone stills draining the battery. My personal opinion… if this phone is not connected permanently to a power source, it will be battery flat in less than 1 hour. Very disappointed.