iMac Pro 2017 Monitor Fails to Start After AASP Dust Cleaning – Black Screen, DFU Restore Fails, Apple Diagnostics ADP000

Shoutout to chatGPT for helping me formatting this in a clear and concise way, since the last couple days were a mess.

Device & OS: iMac Pro 2017 (base model), macOS Monterey 12 (latest version)

Problem Summary:

After bringing my iMac Pro to an Apple Authorized Service Provider (AASP) for internal dust cleaning, the machine began having serious boot and display issues. The first two restarts (into macOS and Boot Camp Windows 10) were fine. On the third boot, it skipped past macOS (despite it being the default startup disk) and booted straight into Windows. The startup animation was skipped and the display appeared horizontally stretched — only the left half of the screen was visible.

Since then:

• The startup chime plays, but the built-in display most times remains black.
• Sometimes the mac boot loops, if it does the screen is always black
• Occasionally the screen turns on after an NVRAM reset, but flickers randomly (black for a split second, then back on).
• Booting behavior is inconsistent. Once the screen works, the next boot usually fails again.
• Apple Diagnostics returns ADP000 (no hardware issues detected), but symptoms persist.
• Attempted DFU revive and restore via Apple Configurator 2 fails with error 4042 (cannot transition DFU state).
• A full factory reset and clean macOS Mojave (default) reinstall did not resolve the problem.

What I’ve Tried:

• SMC reset
• NVRAM/PRAM reset
• DFU revive and restore (fails with 4042, I can’t find what this error means)
• Full factory wipe and reinstall
• All tests were performed with no peripherals plugged in

Connected Peripherals at Time of Initial Failure:

• RME Fireface 800 audio interface (via Thunderbolt)
• USB hub w/ RME ARC controller, MIDI keyboard, Kensington trackball
• External SSD and 3 hubs (2 USB-A, 1 USB-C with no active devices)

Note: This configuration has been stable for over a year. Only change might have been which port each device was connected to.

What I Need Help With:

I’m trying to get the iMac Pro fully operational again. I’m open to wiping the internal SSD (I have a full Time Machine backup) but I want to:

1) Confirm whether this is a hardware-level failure (T2 chip, GPU, display cable, etc.)

2) Know whether this could have been caused by the AASP’s internal cleaning (e.g., loose cable)

3) Understand if it’s fixable without replacing the logic board or GPU

4) Identify any further diagnostic or recovery steps I can take

Meanwhile I brought it back to the AASP a couple hours ago, but I can’t find peace so I’m still trying to figure things out on my own, any help would be golden, thank you