Great majority of Xperia Arc S owners had this problem with their phone, and the official Sony Ericsson statement regarding this issue was that they noted this fault, but they have no idea where this came from, nor how to overcome it.
This auto reboot can be really annoying since you don't know when to expect it.
Sony Ericsson Xperia Arc S users have been serching for the solution of auto rebooting problem, and this is what they've found:
Sony Ericsson Xperia Arc S - Auto Reboot Poblem SOLVED
Xperia Arc S has a fabrique fault - the phone looses connection with the battery, and than it reboots.
All the batteries lay pretty tight in their housings, and althoug it seems there is no chance your battery will loose the connection with your phone - it happens.
This also results in a smaller battery capacity (it discharges faster).
The solution to Sony Ericsson Xperia Arc S Auto Reboot Problem:- turn off your phone
- remove the battery cover
- remove the battery
- put a small piece of paper between the bottom edge of the battery hoousing and the battery (the side opposite of the battery connectors, so the piece of papper pushes the battery towards the battery connectors)
- put the battery back
-turn on your phone
The problem is solved - your Sony Ericsson Xperia Arc S will never auto reboot again, and your battery will last a bit longer!
Sony Xperia Arc S tips and tricks
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