if you have not been specifically trained on this system you should not be attempting to fix it.
You can do more harm than good if you do not know what you are doing. It sounds like someone has done just that.
All the cross check errors are there because the SCON computer is not matching what the DCON computer has stored in it's settings. The only way this can happen is if there is a faulty sensor OR someone tried to change settings during calibration and did not have the programming enable switch on (or circuit jumpered on older models) inside the ground control box.

The safety switch errors are common if the boom drifts out while stowed or if there is a fault in the switches and it will not allow the machine's boom functions to operate till the fault's are fixed. The same goes for the other faults related to the boom functions.

There is a way to lower the boom in emergency lowering using the maintenance key switch, if the emergency batteries are good it should lower the boom down to the ground but it may not completely lower the secondary boom, it is specifically designed to get the operator on the ground when this occurs.
The only way you can get the secondary boom back stowed is to trick the system by switching the jib control and secondary boom control circuits on the function control manifold. YOU HAVE TO SWITCH THE PROPORTIONAL VALVE AND FUNCTION CONTROL BOTH FOR THIS TO WORK. So take the jib control circuit wires at the function and proportional valve coils and move them down to the secondary boom function and proportional control valve coils and use the jib circuit to lower the boom, it should retract before it comes down. This is the only way to get the boom back stowed in this scenario. Don't forget to move them back to the original valves when completed!
Once you get the boom stowed then you can attempt to troubleshoot the safety switch circuits and clear the faults. If the boom sensors still fault out with cross check faults then it will need to be re-calibrated.

It would be best if you called a genie rep to come out and repair this if you do not have the experience to do it, i strongly suggest this over doing it yourself. There are some things the service manual does not tell you when dealing with this system which is why i suggest calling genie out to fix it.

Does the machine start and run, or is it not cranking over at all with many codes appearing.
If it wont start, and has multiple codes, it could be tether line high resistance. This 2 wire cable goes from electrical box all the way to basket. Genie had option to attach tether to driver in case they fell out...Genie techs are not even sure! Its a yellow wire with black or blue, left lower corner of box. Those wires need to be jumped This assumes you checked all switches, fuses, grounds, ckt breakers

Check the electric swivel of the machine mainly if it is the plastic model. For a more accurate teat connect the cables directly without going through the swivel and try to calibrate the machine. If it accepts all the calibrations the problem is really in the swivel. If the problem persists it may be the TCOM board that has problems. In time check the voltage of the traction battery because if it is below 10.5v it starts to present these inexplicable faults.