Hi
According to Canon, Error 06 indicates a fault of the sensor cleaning module.
To work around this:
* turn camera off
* remove the battery
* turn camera on (without battery)
* wait 5-10 minutes
* turn camera off
* insert battery
* turn camera on
If the camera starts ok, disable the automatic sensor cleaning from the menu.
This a work-around to be able to use the camera. But, in the long term, you need to have the camera serviced. Sadly the cleaning module is integrated into the sensor (low pass filter) and I’m not sure if it can be replaced separately. Considering the camera is quite old already, the repair cost might not be justified.
Cheers!
Bogdan