A new riddle Boom

Hi all,

another sick Boom just arrived. Besides a mostly burnt display, it also needed a new power supply connector. But that's not all. It can't connect.
Here is the list of symptoms I could find out so far:

• Logitech logo does not appear on startup. Instead, the display stays dark longer than usual and the first thing I can see is "obtaining IP address"
• the Ethernet (wired) MAC in my DHCP server registers as 04:00:04:00:04:00 which clearly isn't right. But it gets an IP anyway. A device name is not shown in the DHCP server at all
• in the Boom's setup menu (after pushing the "back" button for some seconds):
  
  • I can see both my Logitech Media Servers, however it is not possible to register with them, and the server logs do not show any contact
  • DNS server and Squeezebox Server are indicated to have IP address 4.0.4.0 which is nonsense of course
  • sometimes, the device's own IP address also reads 4.0.4.0
  • sometimes, the MAC address is shown as 00:00:00:00:00:00
  • sometimes, going to the settings requests a setup lock code which is 1024 (found that out while I could go into the settings without the code). Most of the times however, I can get into settings without the code
  • I have changed the MAC address manually to what is printed on the bottom label of the Boom but this setting is immediately lost again
  • setting the MAC is somehow restricted where it shouldn't be. The second digit of the first MAC segment can only be set to 0 or 1 when using the "up" button on the IR remote. Using "down" reveals the values 9, 8, 1, and 0. All other segments work as they should
  • the factory reset available in the settings did not help
  • in some submenus, random horizontal lines appear on the display's right half
  
  
• the display shows two lines where the pixels are considerably darker than in the other lines. They do show the right content. The display is brand-new, the old one showed the same issue. This must be something the Xilinx processor is doing wrong in controlling the display
• Xilinx and factory reset both cannot be triggered on startup, neither from the IR remote nor the main user panel. It seems the firmware jumps right past the phase where these keys would be evaluated (remember the Logo does not appear either)
• running the PCB without the Wi-Fi card, or using a new Wi-Fi card, did not fix it either
• if the Wi-Fi board is not inserted, the PCB ends up flashing "Wireless ca" in huge letters and kind of shifted (see attachment), probably that's the same text as the "Wireless card not installed!" message that pops up every seconds in the first display line in the menu

This reminds me closely of the "MAC not set" issue I had (see https://forums.slimdevices.com/showthread.php?104987-MAC-not-set)
The impression is that whatever causes the behavior is becoming worse over time. Settings are incorrect right from the start, but at least the IP address received from DHCP is valid at first. It gets lost after a bit of time though.
What happens in the MAC setting screen indicates that some data line is corrupted and at least one bit is lost. The PCB does not have visible damage of any kind. From the "MAC not set" drama I remember that desoldering the flash EEPROM and creating a dump of it is likely to prove that the firmware image is actually okay, the issues appear to be more in the region of the CPU or the RAM, however, changing the RAM chip for a new one did not help last time.
Also tried gently flexing the board, pushing the CPU, applied freeze spray, all to no avail.

If only I could trigger the Xilinx reset!

Looks like another death, dammit.:(

Attached Images