If the 4004 is working correctly the NACs are supervised for open circuit and short circuit conditions. Both will generate a trouble. A short circuit condition will also prevent the panel from activating the NAC. This is to protect the panel from damage.
Testing the NAC supervision is easy.
Power up panel and leave in normal supervisory (non-alarm) state.
Remove EOLR. NAC trouble? If yes panel is working.
Reconnect EOLR.
Place a jumper or low value resistor across NAC. NAC trouble? If yes panel is working.
NEVER place a jumper across an activated NAC! Panel damage likely will occur.
Any incandescent bulb is a very low resistance to the NAC so should cause a trouble.
I don’t think the missing diode is relevant at this time. Get one because you will need it to get this working once the socket / bulb conditions are corrected.
I am guessing it was an analog meter that fried. Analog meters are available at quite reasonable prices but can be easily damaged by using an incorrect range or function setting. Digital meters are more forgiving of incorrect use but are also more expensive.