This downgrading method also worked for me.
I used the Handy app to downgrade to 01.08.02.00 then just said yes to the automatic upgrades as they were presented. 01.08.02.00 > 01.09.01.00 > 01.10.00.00. It all worked first time.
Thanks so much to all who contributed to solving this.
If you don’t have the Handy app then follow jsmichau’s path below.
Unfortunately this did not work for me. Via Handy app I downgraded from 01.09.01.00 to 01.08.02.00 then back to 01.09.01.00 and then 01.10.00.00 failed at 48% again. I did the same steps also with 01.07.00.00 then back to 01.09.01.00 and then 01.10.00.00 failed at 48% again…
I can’t believe it, but that actually worked! I finally managed to update to v1.10 thanks to @jsmichau suggestion!!! I really appreciate the help. Looking forward to more great advice from this community!
Have you tried the offline update yet? The “48% wall” usually happens when updating over the network, so I highly recommend giving the offline method a shot!
Not yet. I will most likely try it on the weekend.
Amazing!!! Worked great. Thank you all.
This worked, thank you! 
Sharing so others can search and discover the thread easier.
Tried everything to get from 01.09.01.00 to 01.10.00.00 — wiped and reformatted the SD card, factory reset, offline SD card update, OTA through the printer menu, through Bambu Handy. All failed, always crapping out mid-update.
Found this thread and tried the downgrade method. Used Bambu Handy to downgrade to 01.08.02.00, then just accepted the auto-update prompts as they came: 01.08.02.00 → 01.09.01.00 → 01.10.00.00. Worked first try.
Thank you!
For me the blocker was beta firmware. What worked was using Handy to
downgrade to the most recent non-beta version below wherever I was
leave the beta program
accept each upgrade in turn
This is after some other steps that did not help: changing WiFi networks, cleaning up the SD card, trying offline install, restoring factory settings
Bless you sir, this fixed a week long headache I’ve been having with my P1S