GFI outlet in bathroom doesn't have any power. Test button works, as does reset. Flipped off breaker in garage for quite a few seconds and then turned back on. Still no power?

This is weird, as usually the test and reset buttons only work if the device is detecting line voltage supply to it. If testing the input shows 120 volts feeding the GFI, and there is no output, the GFI receptacle must be defective and need replacing.

Be sure to have the outlet wired correctly, black feed to the Line brass screw, and the neutral feed to the Line silver screw.