RNDU2000 - Seems to be completely "dead" - whats wrong with it

I have a RNDU2000 (ReadyNAS Ultra 2).

When I got it (got it from a friend for free) -

1: When I plugged it in, it started itself up, and then it did nothing, it just are there, blue light, fans on max speed and nothing.

Going into boot menu with reset button or using recovery USB with backup button don't work.

2: I then checked the CMOS battery on motherboard. It was flat. So I replaced it with a new CR2032

After that, it doesn't autostart when plugging in, so it seems Im going forward.

3: Replaced the RAM with a new stick. Nothing there either.

4: Connected a TTL cable as following:

GND TX RX (NC)

on the serial connector on the back.

(the serial pinout is GND RX TX +3.3v, but RX and TX needs to be swapped)

Totally dead on the serial output.

5: On the motherboard, there is a VGA header. I connected a VGA cable, and connected it to a screen. The screen does detect the VGA connection and says VGA connected, but then shortly, the screen goes down in powersave mode, meaning theres no picture output of the VGA.

Any other troubleshooting tips? I guess there is a beep code or blink code somewhere that I can use to find out whats wrong, but guess I need to connect a beeper or lamp somewhere on the motherboard?

NOTE: Theres no important data on the NAS - I just want to get it up'n'running and working, so it doesnt' matter if the drives get wiped in the process. They are already wiped.