Android Enthusiasts Stack Exchange is a question and answer site for enthusiasts and power users of the Android operating system. It only takes a minute to sign up.
Sign up to join this community
It's been said that we can do a factory reset with the following commands:
fastboot erase modemst1
fastboot erase modemst2
fastboot erase cache
fastboot erase userdata
Now, the fastboot CLI provides the following description for erase:
Erase a flash partition.
What does the erase command actually do? Does it erase the partition, or does do a factory reset?
....what is the aim of the "fastboot erase modemst" command?
Answer
modemst1 and modemst2 are storage partitions for Radio Firmware .... - and it's obviously a recommended practice to wipe these partitions when flashing a newer Radio Firmware
fastboot erase system
fastboot erase data
fastboot erase cache
Are explained as
fastboot allows for about the cleanest of wipes by the way. And each partition can be done separately too.
Elsewhere in same thread
... with a lot of new phones
userdata = /data + /sdcard (/data/media), so all data, any personally saved files, and system are flushed out permanently with fastboot's erasure. Note that TWRP factory reset would leave/data/mediaintact
So, putting your list of commands in question, a device is being wiped cleanly of all the partitions mentioned including all data, and thus getting ready to flash a new ROM on the cleanest manner as against dirty flash which has remnants of earlier ROM affecting performance
