Chosen Solution

I have just switched the original battery for a new battery, however several issues are now occurring:

  1. With out external power it will not start up
  2. With external power it reboots constantly
  3. It shows it at 100% charge
  4. It says connect to itunes I am going to try to but the old battery back in again, i tried once before and i had similar issue. Any suggestions?

If you have checked your connections for dock (no.4) and the 2 screws over the battery (1 under the do not remove sticker) are on properly and securely then it may be the old “battery incompatibilty” problem that is common to iphone 3GS. If you connect to itunes and attempt restore do you get error 29? then this would confirm the battery as the problem.try the old battery and see what happens. Why did you replace the battery..was it doing this before you replaced?

wrong battery type, find other exactly for 3GS , i had same when i used 3G battery advertised as 3GS compatible. Random restarts every 2-3 minutes, error 29 etc..