Soft pedal

I assume the brake pressure warning light is also coming on when you press down on the brake pedal.
The first thing you want to do is make sure the master cylinder is full of brake fluid and if it is not, you have a leak, first place to look is down the center of the brake booster under the master cylinder. If it is leaking there the rear seal in the master cylinder is leaking. If not there check at each wheel first for a leak from the brake lines, hoses, wheel cylinders (if equipped) or calipers and then all the metal brake lines.

That could be it, stop the leak, check the master cylinder fluid level and check the brake operation afterward. You may have to bleed out some air if the brake pressure warning light still comes on.

Try tightening up the brake line at it, unless of course it is not leaking from the brake line.

If the seal cannot be replaced and it is part of that proportioning valve, then you will have to replace the proportioning valve.

Anything within that brake system that has a leak could cause a soft pedal.

Why would you want to bleed the front again?
Did you recently have some work done to the front brakes?
No matter what you do, you are going to have to fix any brake fluid leak.
Then after you fix the leak, you may have to bleed afterward.
Note: if and when you go to replace that proportioning valve, press the brake pedal down at least a few inches, then place a stick on the pedal and seat cushion, that way the master cylinder ports will be closed so you do not drain the master cylinder when replacing that proportioning valve.

It could if not leaking from the rear seal which would be visible, then leaking from in between the 2 pistons inside which you would not see, but nonetheless, you are going to have to fix that leak at that proportioning valve first, then bleed.

Numerous things, did you run down the battery?
If not, does the fuel pump run for a few seconds after you first turn the key to run?
Are there any security or check engine lights remaining on or flashing?
Is a security light is on try a spare key or clean the area where the pellet is on that one and try again.
If the fuel pump isn't running, see if you blew the fuse.
Is the engine isn't cranking over and the battery is ok, make sure you are in neutral and/or park.
If the battery has run down, charge it back up or try a jump start.
If all this is ok, check the fuses for the ignition, fuel injection and ecm/pcm.
Then check for a spark or see if the engine will start and run for a few seconds after spraying a couple of shots of starting fluid into the throttle body.