By "instantly", do you mean when power is turned on, or does it blow the first time you hit the flipper cabinet button?

Does the flipper move at all when this happens?

Have you checked the EOS switches?

Sounds like you have shorted transistors locking on one or more coils.

To test the transistors:
Make sure the game is off.
Put the DMM (digital multi meter) on ohms (buzz tone).
Put one lead on the ground strap in the backbox.
Touch the other lead to the metal tab on the TIP122/102 transistors.
If zero ohms (buzz) is shown, the transistor is bad! (shorted on).

I asume you mean one of the transistors on the PPB are hot.
There are a few posibillities.....
It all depends on which transistor is hot.
Most likely the VUK, which is Q3 on the PPB (center transistor).
It can also be the Laser Kick, Q1 on the PPB,
Right Power Scoop, Q2 on the PPB,
Left Power Scoop, Q4 on the PPB,
Or the Ball Launch, Q5 on the PPB.
Either way it is a transistor on the PPB as the fuse is for the 50V power.
When you find the right transistor, check the connected coil.

Data_East_Star_Wars_Tech_Chart.pdf

Yes, the coil or the diode on the coil is bad.
A coil should at least have a few ohms.
In the case of a 23-800 it should be 4.2 ohm.

Did you lift one side of the diode when you tested it?

At 0.1 the coil is toast.
A coil with a molten sleeve is also toast.
Q2 should be the Right Power Scoop.
The drop target should be driven by Q41 on the CPU.
What are the wire colors?

Brown wire coils are directly connected to the cpu.
Yellow-Violet wires are going through the PPB.
So the droptarget coil is indeed driven directly via the cpu.
In this case Q41.
Brown wire is 34V and the Yellow-Violet wire is the 50V which is also used by the flippers.
It looks to me you have two bad coils.