A helium ballon got caught in electrical wire outside, and exploded. The melted debri fell on my car windows. HOw if possible can this debri be removed?

French auto electrics are horrible.

Try going to your local Autozone store and ask them to check your car with their engine check device. It's a free service.
Check your fuses again.

This is probably a grounded starter. You are lucky the fuse panels are intact and it is not melting the fusible link. You may possibly have a bad solenoid or someone put the wrong starter solenoid on the vehicle.
Starter solenoids can look the same outside and be different inside. If this is a new vehicle to you, the wrong solenoid may have been installed.

The main circuit box fuse has blown due to a direct short. Be glad it did, or your car would of caught fire & burned to the ground.

You might find the pieces of harness at a salvage yard. Also you can use wire connectors available at ant auto store. Use a good crimping tool and wrap the splices with electrical tape.

Likly to be a melting electrical part, door lock motor or window switch, wireing cavers. It's possible the car was over undercoated but that would happen before now . Best thing to do is remove the inside door panel and see where it's coming from.

Outside Mirrors REMOVAL & INSTALLATION

1. Disconnect the negative battery cable. NOTE: This procedure is for power mirrors. The procedure for a manual mirror is the same with the exception of the lack of electrical wiring.
   
2. Remove the door trim panel, plastic fasteners from the sound insulator and water deflector, as required.
3. Unfasten the retainer, then remove the mirror trim panel. Fig. 1: The outside mirror has a trim panel which is secured with a screw and a retaining clip
   Fig. 2: Unfasten the retaining screw . . . Fig. 3: . . . then remove the mirror finish panel. Note the panel retaining clip (see arrow)
   
4. Disconnect the wiring connector and remove the wiring from the door retaining tabs. Fig. 4: Exploded view of the outside mirror cable routing
   
   
5. Remove the mirror retaining nuts/screws, then remove the mirror with insulator and wiring. Fig. 5: Pull the sound absorber filler pad out of the door Fig. 6: Unfasten the side view mirror retaining nuts and bolts Fig. 7: Exploded view of the outside mirror assembly mounting
   To install:
   
6. Refit the mirror with insulator and wiring into position.
7. Install the mirror retaining nuts/screws.
8. Route the wiring through the door retaining tabs and reconnect the electrical connector. Make certain the wiring harness does not interfere with the window glass operation.
9. Install the water deflector, sound insulator and door trim panel, as required.
10. Connect the negative battery cable.

learn the hard way ,,, it will need the attention of a mechanic to change all the parts burnt when it backfired and caught alight ,or just write it off and call the scrapyard

check for blown fuses in fuse boxes under dash on left & under hood.check for a blown 'fusible link' a wire leading from battery + terminal to the electrical box near the battery.a fusible link is a wire designed to 'melt' in case of a short.outside of link will appear blistered,and a new one needs to be soldered in it's place.

need to remove the interior door panels and check all the linkages. One of them is a brittle plastic linkage that is famous for breaking, and bits get caught up in the travel path of the door handle. I had taht issue, and rebult all mine with aftermarket plastic linkages, and the metal parts I pulled from junkyard cars. No way to fix it without removing the interior door panels, but that is thankfully a pretty easy job.