Hello,
On my Last action hero when i power i see only the +5 volt led and half a second after i see the blank led.
No PIA Led at all.
I had problem with my old PIA chip and i changed into NVRam .
I keep having an OPen the Door message on the display.
Nothing else.The game doesn't boot.
No sound Either!
Any idea?

the NVRAM was changed due to a suggestion of a pinside member to avoid batteries .So I changed the original PIA chip.
The problem still exists.I have checked the pins for continuity and it's OK.
I have no idea....

Hi @zhu808.
I managed to solve the Open the door display after searching everything.
I have made a post in another topic that explains the procedure that worked for me.
See bellow

Procedures that were done prior to fixing it:
1. Checked D5 Diode (As i removed Battery holder ) ,was ok.
2. Install NVRam.
3. Checked Voltage from Power Supply -Ok
4. Checked Door Switch -Ok
5. Check 6802 Ic- Ok.
6. Burned in Epprom a leon's Test Chip. Installed in 5C and test in work bench results.
7.Alphanumeric Segment/Sound Control Pia at 8B should had pins 3-17 high & Low in test mode. I found that pin 14-17 were low .
8. Install a new socket and new 6821 PIA.

In General you should have on hand a logic Probe, a Leon Test Chip and a Power supply (From old computer power board )
Check Data east repair procedures that are great tool with step to step guidance.https://pinwiki.com/wiki/index.php?title=Leon_Borre_Data_East_CPU_Board_Repair

I found that Pia's are prone to failure. Check them with logic Probe. A schematic is needed also.
I hope i helped somehow.