IMac 2011 won't boot any OS

[Nguyen Duc Hieu]

That can work in the short-term, however baking is not a permanent fix for AMD's stupidity (TLDW: AMD used the incorrect type of solder to connect the die to the substrate, lead to the solder cracking and killing the chip).

Cooking the card in the oven, especially the oven you use for cooking food, can pose some health risks, including solder and flux fumes.

And reballing the MXM card at laptop repair shop is way too expensive comparing to buying another compatible card.

 

[Ausdauersportler]

There is an iGPU on the CPU package, however for a reason that goes over my head, it is disabled and cannot be re-enabled and used.

The HD3000 is not disabled with supported macOS versions (and could be even utilized with Mojave and Catalina), it provides the QuickSync and AirPlay support - but it will be disabled by OCLP with Big Sur and later since functionality broke and patching became impossible. You cannot use the HD3000 to drive any internal or external display in 2011 iMacs.