i have 1st gen xiaomi mi robot vacuum cleaner. it’s been serving very well for the past 3 years.
this video was very helpful with disassembly when i had to replace the main sucking motor fan: https://www.youtube.com/watch?v=wdDSBgJ1kRM
i had to replace a fan and bought https://www.aliexpress.com/item/4000804127893.html instead of https://www.aliexpress.com/item/4000259186760.html ; not an exact fit but with help of plastic strap i got it mounted. we’ll see how long it’ll last.
https://www.youtube.com/watch?v=8FlZgIHOodM
https://www.youtube.com/watch?v=GvaCIRz10T0
https://www.youtube.com/watch?v=ZU5VFpVxj8A