Just blown up my inverter

[EddyCurrent]

"No I never used an earth, the plug has 4 connectors and one of them is left empty (No 4) "

That sounds good and correct.
Pin 1 Phase 1
Pin 2 Phase 2
Pin 3 Phase 3
Pin 4 Not Connected

The spindle needs checking out as cropwell explained.
Regarding parameters I would change these.(when you get the new vfd)

PD014 acceleration time, 1 second is too short in my view, 5 seconds sounds better especially in the early stages of setting up.
PD015 decceleration time, same as above set to 5
PD142 motor rated current, set this to current specified for the spindle, I looked at some and the correct figure seems to be 8.5
PD143 motor poles, I don't know myself how many poles these spindles have but if people are using a value of 2 then it seems reasonable.
PD001 set this to 0 if you are using the keypad controls.

I'm wondering if you have reversed the motor several times without realising it from the front panel buttons, with ramp times of 1 second this may have caused some damage.
As you say, a short at the spindle end would not do the vfd much good.