Powering Onion Omega 2+
I bought onion Omega 2+ and have no dock as of now. As mentioned in the site " How boot without dock" , I followed the same instructions but the Onion Omega doesn't seem to boot up. It just blinks for 30 seconds and then turns off. Is it the power supply or is my board bricked?
Most likely you are using an unsuitable power source. I, too, faced this.
There is a burst of energy required when the WiFi transceiver begins operation. You, as many of us, discovered the magic moment that it happens.
Not knowing your circuit I can only speculate. As such, you may get past the burst point with a "large" amount of capacitance across the power input and ground. Using an expansion dock (which you are not) I'm using a 470uF cap just downstream of a 5V regulator just at the +5/gnd dock inputs (there's actually a small cap just upstream of the regulator as well). This has apparently "solved" my problem, however occasional brownouts occur putting the system in the dreaded 3 byte/4 byte reboot issue (another big topic on the forum).
Try a cap and see if it helps. Additionally reduce inductance (wire length) between the power supply and O2. If those don't help, you'll need a new power supply.