Two different firmware are available for the A5S and A1. There is the official firmware from the manufacturer, and there is a community-created custom firmware as well. There is a big difference between these firmware. If you don't like the community firmware, you can easily switch back to the official firmware — there are no permanent changes made to your pritner.
These printers use the same motherboard, but they have a slight difference, so make sure you install the correct firmware for your printer.
Official Guide: how to flash the firmware, by JGAURORA
Installing the firmware is easy, and it is the same for both the official and the community firmwares.
If you have any problems, please format the SD card, and try again.
Note: The firmware file is automatically removed from the card after updating.
A new firmware has been created for these printers, based of the development Marlin 2.0 branch. This firmware is currently in BETA, as this Marlin 2.0 is still in active development.
If you do try this firmware, please take the time to give us feedback on the forum here. We would like to hear if it works well, or if you run into difficulties.
SINCE THIS IS BETA, IT IS NOT RECOMMENDED FOR UNATTENDED USE!