The JBL Go is a portable speaker, not a power bank.
Please explain in more detail which devices you connected in which manner. A schematic will be of great help. You don't have to use fancy software for that. Make a sketch with pencil on paper and upload a photo (note size limit is ~ 300 kB!).
Also a more detailed explanation of "not working now". What are the symptoms? Do you notice any visual or audible effects?
Actually, I had an unused power supply 5V 2a and I soldered a micro usb and tried it to charge JBL Go and Trust Urban powerbank and somehow they stopped functioning. I had a reading of 5.37v on the multimeter. What possibly went wrong?!
5.37 V is o.k. vor a 5 V port. Not too high to fry components if the polarity is correct.
Wrong polarity? You may have swapped plus and minus. Imho the most likely case.
Or the power supply may have a low quality output with overshoots much higher than 5 V which may not show on your meter but can be deadly for the electronics. Which pinout did you use for the micro USB plug?
Assuming red = "+" and white = "-" the connections visually do look o.k., cf. here. @Fractus : have you verified by measuring that the color coding matches the above polarity? Color coding usually is a good indicator, but not 100 % reliable.
Are you sure there is no short circuit between pins 1 (+) and 3 (D+, center)? USB data is 3.3 V only. A short circuit to 5 V may have damaged the electronics (although a well designed circuit should have some sort of protection against this case).