Upgrading T28P v2.61.13.22 to 2.70.0.130 failing

[NeefRoel]

Hi,

I'm trying to upgrade a recently purchased T28P phone to the latest firmware (2.70.0.130), but this seems to fail.
The currently installed firmware is: 2.61.13.22.

I've tried different methods;
- tftp
- via webgui on the phone directly

Both times the phone reboots and boots up with the already installed firmware.

any ideas on how I can upgrade the phone?