Hi,guys!Here are --
Geeetech A10 series 3dtouch Guide of mine.
Hope it can help you!

Update:

1. Download the Arduino IDE 1.8.5
  https://www.arduino.cc/en/Main/OldSoftwareReleases#1.0.x

2. Download the firmware for your printer,you need to choose the firmware for the printer with 3dtouch
  https://github.com/Geeetech3D/Prusa_I3_3Dprinter

3.Upload the firmware to your printer via Arduino IDE 1.8.5

For the A20/A20M user, you can refer it also.Because they have the same motherboard GT2560V3,same extruder extension board.

For the A20/A20M,you need to add the u8glib.zip to Arduino IDE(A20/A20M use the LCD12864 )
If you don't know how to do it ,refer to my another video
https://www.youtube.com/watch?v=o1QKSgnk_ig&t=164s
Good luck~