There is a very interesting thread from many years ago on this forum. Makes very interesting reading all the way through but if you just want to know how to update the unit to Alpine spec scroll through to post number 43. The instructions are there translated already. Here’s the thread -
If you want the official instructions in English from the Alpine website they are here -
But don’t forget you need to rename the folder.
The firmware to download again from Alpine is here -
https://www.alpine.co.uk/fileadmin/download/Firmware_update/INE-W92xR_W977BT/FU_INE-W920R.zip