I came across a issue where my X10 was not booting and on connecting AC charger, it blinks the Red LED three times at regular interval and On connecting via USB cable with Laptop, still the red LED was blinking, but X10 failed to BOOT
Answer to this:
I took the battery out and measured the voltage with a multimeter, it came out to be 2.9. I plugged into Ac charger, but it didnt increased from 2.9 and Red LED was blinking three times regularly.
Then I connected it to USB cable to laptop (where the RED LED was blinking once at regular interval)
After 10 min I again checked the battery with a multimeter, it was 3.3V.
I waited for another 30 minutes and BINGO. There was a constant RED LED and the phone booted successfully.
I saw strange posts on this topic, but the root cause :: It happens when battery gets completely drained.
THREE TIME RED LED means its not able to charge it.
Hope this helps!!
Cheers!