I decided to play around with my GT-511C3 (which is a fingerprint scanner) for a while. I hooked it up to my Arduino Yun (All my other boards were ~10 feet away from me) and used the "blink" code in this tutorial. Nothing happened. I, not thinking, decided to switch the TX and RX lines. It is a 3V3 model, but the Yun is a 5V model. Previously, the RX line of the GT-511C3 was being reduced to 3.2V, but when I switched them, it was 5V. The power LED went out, and I realized my mistake. I then switched them back. Surprisingly, it turned back on. I then read that SoftwareSerial had bugs with the Yun, and that I needed to use AltSoftSerial. Not wanting to do that, I used my Uno. It didn't show any problems initializing a connection (I think), but the scanner LED didn't turn on. Did I break it (I didn't see/smell any magic smoke coming from it)?
Where did you read the module is not 5V tolerant as I cannot see anything in the datasheet from the Sparkfun page you linked to that says it's 3.3V only.
FYI the UNO is also a 5V microcontroller unless you have modified it to be 3.3V.
The comments+tutorials show that it's 3V3. I know that the Uno is 5V, sorry if I wasn't clear. Apparently, that little module has something that turns it off if the voltage is too high. So, it never was broken, I just hooked it up wrong.
Have you used the wiring suggested? You have to use a number of resistors to drop the voltage down. I had the same issues.
This site helped me wire it up.
http://www.homautomation.org/2014/10/11/playing-with-finger-print-scanner-fps-on-arduino/