Canon PowerShot G9 SD-Card Slot Write Lock.

Introduction

If the Canon PowerShot G9 displays a card error "write locked", it could be simply the switch in the SD-card slot not working.

Remove screw and lift LCD upwards very carefully. Do not put any strain on cables.
Carefully remove flex cables. The left has a flap that needs to be opened (up), the right just needs to be pulled out. Be careful when re-inserting the right one, you can easily damage the fragile cable.
Remove the LCD

Remove screws.
Disconnect connectors for Lens assembly
Carefully disconnect the tiny cable
Next step is removing the PCB. I made the mistake not to take care about the battery compartment switch. If you are not careful, the black lever will break off. Not a problem though, because then the camera will work also with opened battery compartmen
Remove main PCB by slightly bending outward the cover for the jack with fingernail. Now lift the PCB slightly upwards.
Look under the PCB, there is a connector that needs to be separated by means of a small screwdriver or spudger.
Re-attaching the connector is not easy. I used a small screwdriver to carefully press the connector back in place.
This is not the official method to do this. Normally the Top cover and several other parts need to be removed too.

Measure continuity with a multimeter on SD-card slot write protect switch.
If it is not working, short the two points with a bodge wire, so write lock is disabled
Another possible fault is a broken soldering joint holding the case of the SD-card reader in place.