Have you tried to remove the sat cable?
If it's dead have you tried to re-flash it using a null modem cable?
Get the file: "Upgrade_PVR800_HD_Tool.rar", Unzip this file & you have a folder with 5 files:
eromclient.abs, flashburn.ini, sdram.ini,
LZMA.exe & eromUpgrade.exe & helpfile.txt.
1. Connect up your PC to the Openbox using a null modem serial cable.
2. Switch the box OFF
3. Run EromUpgrade.exe then check the com port setting is correct
4. Select the latest firmware .abs file. (Download here if you don't have any)
5. Select "next" then switch ON the box and follow the instructions to load and flash burn the firmware.
6. If the process does not start, try various time combinations of switching the box ON after selecting "next"
7. Don't switch the power off or disconnect while the download & flash is taking place.
I will add in the upgrade tool later, just in work so can't get access to it until I get home.