Reprogram Volvo V90 remote

First, if you have tried cycling the swith 5 times and it doesn't work, that makes me believe you have a transmitter that isn't the correct frequency as needed. Since one worked and the other didn't. That tells me you know what you're doing but one doesn't work. On the underside of the remote, check for one of these part numbers:

9128927
9128709
9148646

If it is different, return it and request the correct one. Keep in mind, even though you waited too long, the reciever automatically erases an old code to add the new one, so you didn't do anyting to harm the system.