Hi,
At 3.3V and 3.6Ohms there is a current of about 0.9A, giving a power of about 3W. That is much heat that you can feel with your fingers. Be carefull.
If you don't want to test with 0.9A, then you may use a current limiting resistor. Maybe 100 ohms to limit to 33mA.
Use a mV meter, connect Gnd to Gnd. With the other wire test several points (starting near your power supply) in your 3.3V line. The lower the voltage, the nearer is the bad connection.
Hope this helps
Klaus