Hi there,
for mk2 please follow these instructions:
- Disconnect the USB cable
- press and hold the right-bottom button on the E1
- while keeping this button pressed, connect the USB cable
- The bootloader screen will show up
- Make sure the firmware file is uploaded (if not reupload it using the E1 disk mode)
- Tap on the firmware file. Please, make sure you tap the file without any leading ._ characters.
Please let me know if this helped. If not, I am available to help further.
I will update the docs accordingly.