Symptoms

Cannot interact with K2 smartobject - Error internal loop: ServiceObjectMethod
 

Diagnoses

a K2 smartobject that was integrated to a K2 connect Service object.
The K2 connect Service Object was changed and since then, any and all interactions with this smartobject failing with the following error:

Error: Deserializing Type:
'SourceCode.SmartObjects.Authoring.SmartObjectDefinition' Name:
'CLIENTS OBJECT NAME' Message: 'Error internal loop:
ServiceObjectMethod'
Source : SourceCodeSmartObjects.Authoring

This error comes up in the SMO Tester when trying to delete the SmartObject.
Also in Object Browser when trying to expand the category where this smartobject is located.
 

Resolution

Support does not recommend deleting of a SmartObject please see the below link.
http://help.k2.com/onlinehelp/K2Appit/UserGuide/current/default.htm_SF-SO_Deleting_a_SmartObject.html_tracksearch=delete smart object

See below script provided and thoroughly tested on a VM.

DELETE FROM OK2].2SmartBroker].rSmartObject]
WHERE RSmartObjectGUID] = "CLIENTS SMART OBJECT GUID"

This removed the SmartObject successfully.