HP E4433B SRAM failure again?

[Oldtestgear]

I have 2 of these showing the same fault. According to the service guide the LEDs are showing that the BOOTROM RAM test has failed.  It powers on but does not get past this point. It seems that there are 2 RAM chips fitted & I am guessing that the HM628512 is the likely culprit. Has anyone ha experience of this failure mode & able to offer any guidance or am I just plain unlucky. I also have a 3rd one that may have the AWG SRAM failure as well. Ironically the 4th one I bought has a dead RF output but at least there is a bit more information on this one.

Any thoughts appreciated.

Phil