Hi, It sounds like you didnt have the ylod and then caused it by reflowing the first time.
When you have a ylod the ps3 will just shut down either on boot or soon after. The light will go from solid green, to a single yellow blink.. then will continually blink red.
First thoughts from your description would be you or someone was using hdmi to output to a tv now you are trying to use a scart cable when the ps3 is set to hdmi mode.
Try this solution, all credit to SUPREM_KITE over at neoseeker!
ok try this. turn the ps3 completly off and then put the scart cable in. now turn the main power switch in back to the on position and then press and hold the power button by the disk tray you will here the ps3 beeb, keep holding till you hear a second beeb. this should reset it to use whatever cables are in the system at the time it also may take a minute.
If it doesn't work first time try again with another cable sometimes the ps3 is picky with scart leads.
Hope this helps but like i said before i could be completely off the mark with your vague description.