thats weird..did u try to purchase from your nexus 7 instead? you can choose the google wallet balance rather than credit card..

have u restore back ur nexus to factory? u need to restore it first then follow the step by step...if u already do the registering before and already get the free 25usd, u need to reuse the same google acc u registered, and follow the step again...maybe there is something goes wrong or mistake when u do the registering...i'm also having the problem bfore n google already lock my google acc because of weird activity...then i just relock and reuse again...the problem solve...try it first

delete ur credit card first.
then u can change home country.

Unfortunately, users with a Google Play balance or a Checkout Merchant account are unable to change the country.

It is an open secret that many non USA based users has bypass Google limitation and manage to get the us$25. I find it strange Google allow this. It is impossible they are not aware of such a stunt
I would think k they have purposely allow such practice N now decided to pull the plug off such faked users
For those users who have successfully got the us$25 and spend all of it, it was indeed a free gift from Google
My experience was seamlessly smooth, thanks to forumer yolk well written guide. Now only left us0.13

mine 1 will freeze when using Chrome browser with GOkeyboard.

omg I jus saw this at google wallet help
there is no way to spend the balance until $0 right? so there is no way to change our region back? 
so its only matter of time all the account get banned for the $25