MP 1,1-5,1 Mac Pro 4,1 (2009) only booting into recovery mode

[janpieterduhen]

Hello, hope anyone has a tip to get my Mac Pro 4,1 booting into the OS.
Symptom: no matter what I try, this Mac keeps just booting into recovery mode. (GFX are fine, nice gray screen with apple logo -> recovery-mode)
Failed attempts so far:
- remove all disks and do clean install from USB-stick OS Lion (also tried El Capitan) onto a brand new HDD. Installationproces goes well (first reboot into installer, installs all files on HDD, 20 min installation time, second boot it should boot into the OS. nope: Recovery-mode
- Used an other (apple) graphics card (original GT270, other RD5870), boot into recovery-mode
- Tested all separate memory-modules, booting into recovery-mode
Anyone a suggestion on how to get this machine working again. Greatly appreciated!

 

[Matty_TypeR]

Have you cleared the NV ram? hold option, command, P + R keep holding let it chime 4 times before letting go of the keys. also check on board BR2032 battery, once it drops below 3v it can cause all kinds of issue's.

 

[janpieterduhen]

@Matty_TypeR thank you, I thought I did the NVRAM reset, but can not remember hearing 3 chimes. Will try again. I replaced ghe BR 2032 with a new CR 2032 but that didn’t make a difference

 

[Matty_TypeR]

NVRAM reset make sure you hear 4 chimes one after another, takes a little while and the CR2032 will not last long, should be a BR2032

 

[janpieterduhen]

NVRAM reset make sure you hear 4 chimes one after another, takes a little while and the CR2032 will not last long, should be a BR2032

@Matty_TypeR NVRAM reset did the trick. I think I released the keys a bit to soon the first time around. Thank you! MP working like new!