Instead of randomly chasing grounds, you should try testing at the O2 sensor connectors, then chasing from there. Here is a link (not sure this is totally accurate, but seems well written):
https://troubleshootmyvehicle.com/jeep/4.0L/P0135-diagnostic-tests-2
Measure for proper voltage and ground at each connector and report back.
Also, you mentioned that bolts blew out or something after you replaced the O2 sensors? Are you sure that they are installed correctly? Air leaks at the sensors will cause error codes as well.