Evil mastermind PhD Evil, is trying to destroy the north pole. In order to foil his plan you need to log on to his computer. Alas you don't know the password, thankfully PhD Evil thinks he is too clever. So he left a puzzle to solve his password.

It is ten too.
My password is seven letters long
four letters is also not wrong

It is fair to say that it is none
but that could be off by one
If you think my password is a single hole,
I will blow up the north Pole!

Your partner says, I don't really care the north pole is fake. But you persevere for Santa's sake.

onezero (10 or ten)

10 in binary is 2

It is ten too.

10 in base ten is 10

My password is seven letters long

"onezero" is seven letters long

four letters is also not wrong

(maybe) 10 in Spanish is diez, four letters

or (credit to Niktheslik)
One zero could be interpreted as just "zero" which has 4 letters

It is fair to say that is is none

but that could be off by one

0 is none, but it is missing the 1 in front of it

If you think my password is a single hole,

I will blow up the north Pole!

0 (single hole) is the wrong password

• A better explanation for four letters is also not wrong: zero is 1 zero, as in a singular zero. So one zero is, in that sense, equivalent to just zero as a zero is 1 zero. Jul 11, 2016 at 19:43
• @Niktheslik Perhaps but in that case the password is the string "onezero", which it might be, I'll edit my answer to include it
– Axle
Jul 11, 2016 at 20:12
• I like this solution. About the "four letters is also not wrong" explanation, it could be: "Deca", which is a metric unit prefix indicating ten multiples of the unit. en.wikipedia.org/wiki/Metric_prefix Jul 11, 2016 at 20:42
• @Axle onezero is indeed the intended solution. Well done. Jul 11, 2016 at 20:47
• I think four letters is 'onez'. Jul 12, 2016 at 6:10