The most common issue with PIN numbers is mistaking two characters that look alike, for instance a capital "i" might actually be a lowercase "L" or the number "1".  Similarly, the letter O can look like the number zero.  Are there any characters in your PIN code like this?  

If you are using the Mini 2 then you can read in small letters under each large letter what the actual letter is. So far all customers that report this issue find that they are interpreting a letter incorrectly. However, if you would like to generate a new code you can do that if you are using the Mini 2. First, you will need to plug in a USB Keyboard into the Mini 2. 

Press: Ctrl+Shift+C
Next Press: Ctrl+Shift+R and the system will restart with a new PIN