APC BP1000, missing front panel

[Scrufdog]

Hey everyone. Found you on YouTube. Watched episode 504, tear down of an APC 2200 UPS. Figured this would be the best place to ask a question.

I came across an APC Back Ups 1000 Pro (BP1000) with dead batteries, and missing the panel switch/LED panel. I dropped in a couple batteries and plugged it in. Single beep, couple clicks, and a hum of the charger, charging properly. Checked various voltages here and there and everything seems ready to try. However, without the front panel, no on/off switch...

I have 118vAC up the main relay that turns on the outlets. I can't find any schematics for this unit, but the couple I have found for other models with a ribbon cable, make me think of the 8 pins, one of them is looking for a momentary GND signal to turn on. Before I just poking pins with GND, any recommendations for me? I figure if need be I'll build the serial control cable for it and try turning it on with my laptop.

Here's what I have found on the ribbon cable...

Pin 4 - GND
Pin 5 - 4.4vDC
Pin 9 - 4.9 vDC

Thanks for any help you can offer.

[Scrufdog]

Update, to fix my mistakes and update what I've found

Reference http://eevblog.com/files/apc_smart-ups_su2200_3000.pdf for the schematic I'm looking at.

So it turns out the SU2200 (which I got the schematic for) has very similar circuitry as the BP1000, down to many of the component labels and numbers.

I found that I can tap jump ground to the J11A Pin 6 (labeled as the On switch on the SU2200), I get a short beep and 10 seconds later relays start clicking, and I hear the inverter turn on. The voltage at the main output before Relay 1, goes from house 120 to 230v, and holds there for about 5 seconds. Not sure if this is a diagnostics test, since I cant see what the front panel might be doing, and I've never had a UPS that had a built in diagnostics mode. At no point can I get the main relay to pass voltage to the outlets. I've checked both sides of the relay's coil and both sides are always 24vDC. One side is connected to 24vDC supply, and the other to a series of switching transistors and the main control IC. From what I can gather after clearing my brain of the dust on my electronics knowledge, the circuit should pass ground to the 'negative' side of the coil, unless 'commanded' by the IC to shutdown. I'm getting a constant 4.0vDC from pin 25 of IC12 and 0.5vDC on the base of Q45. 24vDC on the collector and GND on the emiiter, of Q45. Q44 base and collector are 24vDC and the emitter is GND. If I'm thinking right, the base of Q45 needs to go high (24vDC) to pass ground to the base of Q44, thereby passing ground to the 'negative' side of the relay. Pardon me if I'm wrong, its been 20 years since I took Electronics Engineering. Assuming this is true, I'd say that IC12 isnt putting out the turn on signal for whatever reason, possibly because it cant talk to the board on the missing front panel.

Anyone care to take a look and offer advice?

Thanks