Seal U DM-I - Dashcom hardwire installation (no OEM dashcam)

I had an installer advise that I check with BYD to ensure installing a non-BYD dash cam does not void the warranty. I'm too lazy to have done that yet but it is on my jobs list.

What should it void the warranty on? It's a serious question

Cars these day are a myriad of computers and electronics; unless free fuse slots are available to draw directly from the battery, you could be damaging components with under voltage by sharing. The manufacturer is within their right to void any and all warranty given.  You can also introduce false positive faults because the car senses by known voltages to determine issues. You also might force systems to stop complying with local regulations. Like when people replace halogens with LEDs and don't add resistance to compensate for the difference; now their lights blink at a faster rate, which in my country is a non-compliance issue that you can be fined for.

Yes, that may be possible. Since the system has an OEM dashcam available, I would assume you can connect any dashcam to the same circuit and be fine. The question is, how is the OEM dashcam connected?

The OEM plus directly into a module behind the glovebox. I fitted the OEM camera which then shows up as an icon on the drop down menu, it also gives more information than a normal dashcam like speed, indicating and braking. The camera quality isn’t the best but it does the job.