As you’re probably aware, I love to tinker with phones, especially Android ones, having been able to root several:

  • HTC Wildfire
  • HTC Sensation
  • Asus Transformer TF101
  • Samsung Galaxy S5

However, when trying to tinker with my dad’s S5, some really weird behaviour occurred. I first unlocked it using a SIM unlock code, and it started to randomly reboot. Regardless of whether or not you use an EE SIM or not (we tried EE, Virgin and Three SIMs — all were subject to the rebooting behaviour). So, I decided to take a change and rooted it and flashed Bobcat ROM (a ROM which I was running successfully on my own S5, which is the same model as my dad’s with the only difference being the network provider — I’m on Three, he’s on EE.)

The phone still randomly rebooted, so I turned on Logcat and tried to see if it recorded anything. No such luck.

So I tried a few different ROMs — Stock Samsung (Lollipop), Bobcat ROM, and Phoenix ROM. All still rebooted. So I took it to Samsung for their opinion. They said they couldn’t flash it because Knox was void (Knox is a warranty flag on Samsung devices which indicates whether you have custom flashed the device or not — I obviously have.) But they were nice enough to tell me that the behaviour described usually indicates the Firmware is wrong (which is something I didn’t flash).

So, since this behaviour started before I even did a deep-level tinker with the device (before I flashed anything), I can only assume EE either flashed an incorrect firmware, or did not flash the correct firmware – or maybe did not flash the firmware properly. I now need to find an S5 firmware to flash onto the device. Since my own S5 is working, I can check that firmware and try to find the same one.