Installed a brake paddle lock. Once locked, the gear stick immobilized. Current to the ignition disconnected. No wire cutting.

If yours is not connected to the electrical, there is no reason why MMM should void your warranty. Absurd. Does that mean if I install mud flaps on the car they will void my warranty. Totally no basis to void the warranty.

Even if it is connected to the ignition it is just a wire by pass to break electric when the lock is engaged. They is no wire cutting and joining required in the installation.

If I were you I'll write to HQ and state my case. If they still void the warranty, then I tell them I take the case to Consumer Tribunal Court. You just have to pay RM5 to have the case heard in the Court.

https://ttpm.kpdnkk.gov.my/portal/index.php/en/

Yes, I did the first 2 services. Had the HU fixed a few times but in the end they changed a new HU for me after I wrote to MMM HQ to complain about the reverse camera always malfunction.