@valle_der_wolf let’s start off with some basics first.
Common Reset Procedures
When a reset procedure is required for troubleshooting, follow the applicable steps:
Resetting the System Management Controller (SMC)
To reset power management via the SMC chip:
- Unplug all cables from computer, including power cord.
- Wait at least 15 seconds. The SMC reset occurs automatically once the Mac mini has been unplugged from AC power source for several seconds.
- Plug power cord back in, making sure power button is not being pressed.
- Reconnect keyboard and mouse to computer.
- Press power button on back to start up computer.
Resetting the SMC means you will also need to reset the date and time (using the Date & Time pane of System Preferences).
Resetting the Parameter RAM (PRAM)
To reset PRAM,
- If the computer is on, turn it off.
- Locate the following keys on the keyboard: Command, Option, P, and R. You will need to these keys down simultaneously in Step 4.
Note: If the keyboard does not have an Option key, use the Alt key instead.
- Turn on the computer.
- Press and hold the Command-Option-P-R keys.
Important: You must press this key combination before the gray screen appears.
- Hold the keys down until the computer restarts and you hear the startup sound for the second time.
- Release the keys.
Starting Up in Safe Mode
A Safe Boot is a special way to start Mac OS X when troubleshooting. To start up into Safe Mode (Safe Boot),
- Make sure the computer is shut down.
- Press the power button.
- Immediately after you hear the startup tone, press and hold the Shift key.
Note: The Shift key should be held as soon as possible after the startup tone but not before.
- Release the Shift key when you see the screen with the gray Apple and progress indicator (looks like a spinning gear). During startup, ”Safe Boot” appears on the Mac OS X startup screen. To leave Safe Mode, restart the computer normally, without holding down any keys during startup.
Unlikely cause: hard drive, optical drive, speakers, camera, microphone
- Check display connections
- Check connections for pin damage.
- Reset SMC.
Go to Deep Dive.
Deep Dive: No Video
- Verify boot chime present and fans running when system powered ON. (Reset SMC and clear PRAM if necessary for proper boot up.)
Power ON self test OK. Boot sequence started.
Go to step 2.
Go to Won’t Start Up symptom flow.
- Connect supported external display via mini display port. Verify whether image appears on external display when system is booted.
Video present. Verify system functionality and return to user or jump to appropriate troubleshooting flow.
Go to step 3.
- Connect supported external display via mini-DVI port. Verify whether image appears on external display when system is booted.
External display detected by system. Video circuitry on logic board functional. Return to customer or jump to appropriate troubleshooting flow.
Replace logic board. Retest.
There are no schematics available for the Mac Mini. So we rely on you to let us know what 820-xxxx your logic board is etc. so we can possibly find a board to check components etc. if that becomes necessary. Let us know what you find out when you perform the checks.