Avalon cedar fireplace shut off issues

[Smileyfaces]

We purchased a used Avalon cedar propane burning fireplace. Since getting it home and setting it up we have had numerous issues. I finally got it to light and stay burning but only without the logs in the firebox? If I put the main backlog on it it will shut off after about a minute of burntime everything goes out including the pilot. If I leave the back log off it will burn continuously with no problems, put a new thermal pile in yesterday. Any ideas on what is causing this? Also now that it burns the rocker switch on the back does not work I can only turn it on and off for using the knob below and turning it from pilot to on, manually, it has a thermostat hooked p, but that doesn't do anything either. Any ideas??
Finally, when it does burn, it creates tons of soot in the firebox, the glass turns black in no time at all, what generally causes that?
Thanks for your insight!!

 

[DAKSY]

The rear log may be creating too much heat around the thermopile Try elevating it maybe a half inch to allow for the heat to dissipate.
Pull the wires off the switch & hold the ends together. If the unit comes on, the switch may be bad. If it doesn't come on, the wires are suspect..
I concentrate in that direction (wires) since neither the switch or the t-stat function...
The sooting is most probably from an improper ATF mixture. Soot is caused by a lack of air causing a too rich condition. Check the burner for an
adjustable air shutter. LP requires MOST air shutters to be WIDE open.

 

[Smileyfaces]

The rear log may be creating too much heat around the thermopile Try elevating it maybe a half inch to allow for the heat to dissipate.
Pull the wires off the switch & hold the ends together. If the unit comes on, the switch may be bad. If it doesn't come on, the wires are suspect..
I concentrate in that direction (wires) since neither the switch or the t-stat function...
The sooting is most probably from an improper ATF mixture. Soot is caused by a lack of air causing a too rich condition. Check the burner for an
adjustable air shutter. LP requires MOST air shutters to be WIDE open.

Ok, so I need to ask, on the air shutters, here is a picture of 1 of 2 flaps that are on top of the fireplace located under the grate(top). One picture shows what it looks like closed

 

[DAKSY]

I'm not totally familiar with your particular unit, but if those doors are located at the top of the firebox, they are most likely "blow-off" ports. They will open if there is too much pressure within the firebox at ignition, which will prevent the glass from blowing out.
This happens when the gas builds up before the piezo spark ignites it. LP (aka Propane) is heavier than air & will pool in the base of the firebox below the igniter.