U27 appears to be some kind of storage (EEPROM or FLASH), most probably with configuration data for GL3523. If it stops working then the USB hub will operate with default settings, which are no good if the configuration storage is present in the first place.
Could you have damaged it? Probably yes, but for now let's hope not.
It is very hard to tell what the marked component was. Almost certainly a capacitor, but which one?
Have you tried measuring the capacitance of that speck of dust?
I am guessing this is one of C244- C246, as it is close to DVDD 1.2V input pin.
There is a high chance the hub should work without it, perhaps become a little less stable. However if you damaged the trace reaching pin 47 in the chip, then it surely will not work. It should have 1.2V.
Here are some DC voltage measurements you can try to debug the issue.
All measurements to be done relative to GND.
#1-2 are L10, #3-4 are C243, which are parts of 1.2V Buck converter.
#5 is pin 47, which uses voltage from 1.2V Buck. Be very careful not to short it to neighboring pin with a probe!
#6-#7 are C256, which provides 3.3V to th memory chip.
If your multimeter can measure frequency, try measuring it across capacitor #8 - it should be 25MHz.