If that 9V battery was able to charge your cellphone battery, odds are you fried it. Lithium batteries need to be pulse charged and at a proper voltage so that 9V battery was more than double what it can handle. It may have worked temporarily but you most likely damaged that cellphone battery. Use a multimeter, set it to DC volts and touch the corresponding contacts with the probes. It should read anywhere between 3.6v and like 4.4v