Re your other problems,
First suggestions, which are not entirely relevant but may be helpful, sorry if this teaches you to suck eggs, how tos litter you tube
1. Fix Id (will help if you lose comms and then reconnect)
2. Change failsafe to drop the throttle (out the box failsafe on the runner/devo7 is set to "if you lose comms the quad will bu**er off and never be seen again"
3. Fix flip of death (fod) (increase throttle trim and enable throttle hold)
Next an observation:
The runner 250 has a 1mm carbon laminate top and bottom frame, this is thinner than most laminate frames and not as strong as pure carbon frames, if I compare it to my QAV, that has 3mm pure carbon top and bottom frames, three times as thick and made of stronger material
To compensate for this and give the runner rigidity Walkera have integrated the pdb into the structural integrity, this gives it rigidity, but means the pdb tends to get broken very easily, the generally accepted solution is to double up on the two long plates, the screws are long enough, costs about 15-20USD for the two pieces and vastly increases the strength
All that may sound like I have a downer on the runner, I don't, I bought mine to learn Fpv whilst I was building my QAV, I still fly and enjoy flying my runner. That lot is what I would suggest to anyone buying it though
Re your problems
Props covered in other post
Crash - the fact you have lost an led and one motor, assuming there is no obvious damage to the led, smacks of damage to the board.
Hold the runner up and look from the side, is the board flat and straight?
If that still doesn't answer your problem. Take the motor off and switch it with the opposite one, it should just unplug and unscrew.
On my original Runner the front left and rear right motor wires come straight out to the esc. Red to red blue to blue and black to black. The other two have one pair of wires crossed.
Depending on which motor is spinning the wrong way (I will guess front right or rear left) you will have to unplug two wires and swap them on the Esc. The wires have bullets and slide out of the esc easily. On mine I have the blue wire to the black label on the esc and the black wire to the blue label on the esc just to let you know. It shouldn't make a difference which two get switched but after all it is walkera and they are very proprietary so mays well stick with their wire scheme.
Let me know if that works if not we can check other things.