Hi uali,
This issue is quite simple. I will try to explain it to you.
When you execute 15 consecutive resets the device stay in permanent reset. This is your case. To recover from this state you need to execute power on reset.
I expect you do not disable SWT in startup (assembly code).
After Power on Reset(POR) the default timeout for SWT is 20ms. If this expire SWT module resets the device. If this happen 15 times -> device stay in permanent reset until POR is executed.
So to prevent this you need to dissable or service SWT during these 20ms after POR.
Now the Lauterbach issue:
If you are able to attach with lauterbach during these 20ms x 15 times = 300ms then Lauterbach will disable the SWT automatically.
As this is a short time and usually you are not so fast with attach of debugger the micro will assert a reset after 15 SWT resets and you cannot connect until new POR.
Solution:
1. Connect with debugger within 300ms
2. Hold external reset, Power the board, attach with debugger, do break, and release the external reset.
Hope it helps.
Peter