Ford Repair: trouble bleeding brakes after r/r of broken caliper, piston head, bleeding brakes

Question
1999 Merc/Villager 3.3L, 144kmiles. The rFrnt piston head broke and bled out till the brake pedal hits the floor bd. 16 yr old driving the vehicle (he drove the van for at least 15 miles & many stops before informing me). After changing out the caliper and pads, I can't get any fluid to flow out of the bleeder (pedal pump bleeding). The fill resivor was very low but not empty (filled before bleeding attempt). Cracked the LRear bleeder - no flow. Looking for next steps.  Thanks.

Answer
system is slap full of air-try gravity bleeding first-fill master cylinder and open rr bleeder then patiently wait until fluid starts coming out it may be a while-when it does let it drip for about 5 minutes-make sure master cylinder does not run out of fluid-try this on every wheel one at a time after you start getting fluid out of all of them (still one at a time) then you can bleed system-