Visual Studio Devenv.exe hangs when you attempt to open a SSIS package. Make sure you have Delay Validation properties set to False, though if you are at this point and still not responding, that won’t help you. Try setting the max degree of parallelism on the SQL instance back to 1 (if it is already set to the default of 0). No need to restart the instance, just try the code below to make settings effective. You may need to kill devenv.exe though, then open your solution again, and try opening up your package again.
EXEC sp_configure 'show advanced options', 1; GO RECONFIGURE WITH OVERRIDE; GO EXEC sp_configure 'max degree of parallelism', 1 GO RECONFIGURE WITH OVERRIDE; GO