Forms broken - FormDesigner error

This issue may be similar to a few other post on the community. May I recommend trying to export and import the form. 

Do you know if there is javascript or some code on the form preventing it from opening?

Also attempt to open it within another browser to see if something was cached or set preventing it from rendering now.

The problem is, that i am not able to export/import it because i cant open the Designer..

I know there is something in the Script part, but dont know what.

Already tried another browser. Without success.

Nobody can help me??

try to open developer console and set a breakpoint in the code you where you expect there is a problem. once the execution breaks, try to change actual values of variables so that it jumps out of cycle.

you may want to watch network traffic to see whether it's not looping in some request from server.

if do not succeed with above you may try to export form with a webservice call

https://help.nintex.com/en-US/sdks/sdk2013/#FormSDK/Topics/SDK_NF_API_REF_GetFormXml.htm%3FTocPath%3DNintex%2520Software%2520Development%2520Kit%7CNintex%2520Forms%25202013%2520Software%2520Development%2520Kit%7CNintex%2520Forms%25202013%2520SDK%2520Reference%7CWeb%2520Services%2520Reference%7C_____3