[Galaxy S III Q&A, Help & Troubleshooting] chafik94:
I managed to repair my phone today, apparently it was a faulty battery, i used a naked charger to revive it (took off old charger's phone side as shown in the picture, stuck the Black wire to the metal above the positive sign, and the green wire to the one above the negative sign, placed the battery on the phone with the charger in between them and plugged it on the wall for a few seconds, and the phone turned on just fine),

[IMG="Modified charger"]https://lh3.googleusercontent.com/dY5VAnHIE_INvTe8PUF_7AjDO0Mi-C1FaWIfmpK1Y6haMJvNd1eUzTEmWLtuMLvvl8WexODiEycNr38IRNAZPhMC-30rP8wDQqgnobHdjG9QrFvSWvNuo9Sp0369OmGnnKyDfhEiLyTCskFrVx5il6P6jimnRQH_NDIp2IeA7nQN8t7vX4ARfJY8xH2YuRZHy2zwZthQlT9VlPrp7k-dxcCqof8mrKPOZe6KKSVCWKG7ZrjG35BVzqBa3KjIZDS4Rqs2N88DIEJghY0HrVt2TIPt3M4i2Wa8z0ERb1TTt6QEKCQqRYYeDwp_IrMQfCTSkadbshIqZPWD1ZIGwQFetggT8t1ac92NDhMAJkMr7fy5H052nzJrDoh0iWPkO1cs6BomeXbaorPIQQIoqMXdINSFEZX3H6Ya9H19GqDxbbvpjRv93Hp83aCPJRDXHSzQc9xR6Tph2KtWr0Sbb0f55J8UDcVdHcFAnrIxH-zfY-swvEBxskwSPKO9JQeM_dsFXFAkFNbjV9GflvY6wh4bloYfi34QkdXHALISpMnL0jUmaQzU5OKXOm9OM2gaTa4IhjcONYmp_rl5aieDM5X2ikZ518g12sE=w450-h599-no[/IMG]

[IMG="Battery"]https://lh3.googleusercontent.com/MSanRAZnp7VuTFIxzMDPtpmRjf9M1mzWg38GaXgmSnDC4kPfDh-v9SCdRBcwv6FFREBINNwigG0auoRbf-GIp5jDg1aqMMlwBhBKaoOV06HUHIEGL2nUI8N33GN93GqUd2fQY9RPBme0SvJvLdTECNikDhGPrsVEbosr88UhX1bu9FbBYpao-7eHxib_NSTL5RMbJKpnw8X_V6msWrVAy7DG00_I2FmgBPIt-nfvEI74i1OkCLK906D-RQTcK9nsjl-EtiRCHHGSZIacMXPwdR_Wnwb5z6A0-1fDawr8NyOki2FLwbE5b16QReiRM9iaU9qRs7d2UcF9Uh7JqhtWoJrOWO288-mvHYgQRElcep7ZIsgL4qgQ_SRWaX-Ob7dcu1EIdig9SVhEhP-FYH_qIgTjI7AmtilgABgeDuaD8XYCEnqimjkWzxxoNMB4MHAhAF3ptLtPofMfti5YvPKIZ8gjmByLOd53YrxPdQdTo1ew0RydJTX2WzIupUVnfk3ZKgw0CYCwuV77FEoJ0aejQitS2QHHx8AznMEDd5ldGjgvzG14fOMind6eOtd2228SQbGWhk7-XsuWeaK4pLAJ_3hoKRYs4wQ=w483-h643-no[/IMG]

i re-applied the firmware and this time the android robot where the phone used to shutdown while installing, now completed it's job and the phone rebooted normally, I noticed a yellow text overlaying on the screen, done some more research and found out it is called "Factory mode" (I am a noob you know) so I had to Root the phone to get rid of this problem and this time, thank the Lord, I succeeded in rooting it because I double checked everything lol.

BUT..., Lol when you screw something up, you just have to keep patching it, you fix something here, an other problem appears over there hahaha.

anyways, the problem now is the network, I do have signal and it changes when i put the phone in different places with different signal strengths, and the clock is perfectly updated, but i use the phone as a phone and call people, it gives me this message:

[IMG="Not registered on network"]https://lh3.googleusercontent.com/4oVchCVaMS7hcxRTt8437zh2hlvgbynpIG18b4xaJSRWv5eCoAiGqQdOBjjK_4YE9xEfHOvnZNV994iqAq4MAP1FIu3M6ABxfndwr67jaeAchBhtdbotUBTDTjBePhmu44sftSE8MlPjEdyNYbQE0WzXoEyBVrjfgsvu-bcopUIuOFgyGjG2rmS9Qa0D1SsXmlNLMYwdnItx7cKgOzUi-vxozFnHPSj74SSqtau9DRoAXwWJndDEIAiYxWy2VmWyJJe8CqJnZbi3cpL_tmWxsgSqb0bKJpH2qJRLj3LYDHwZ5def1Q9ckd0PaEqkcj6JbSscHx_VzQF9ISz5ZU7HAG8tzw1SHL90LxinJL1X27LOvRKLUin5JE4eEQPHIBeYYiWhnkRUwGVK-n9LE3Vtdni4s8LPV4wdsFwloLPt6dpeTsjwoXkJAfl6kcOjK8ewztlpvT8IF0p4Yh1DVF6C9-ijJgadwBhFqxUggb4pb15wJYpz0Tzx0AlHlp1X-FivWBztrXUbK97GZxm4HcFeLLhsiS_n9diOcnP85yq0LHM_9PEc5w9eVsV9L_keo_CvzVHlIcrJ5vRU7EuVKB6ep_gzvqSuU9w=w362-h643-no[/IMG]

I tried allot of things trying to fix it, nothing seemed to help, and then it came to my mind that probably what I did wrong was download my Service Provider's firmware, maybe the phone Had the international firmware i can't remember and i didn't check it before, the friend i bought it from just told me he brought it brand new but not from a service provider which means it had an international firmware, so now I am downloading a firmware from sammobile that had Unknown in Country, and here's its full title "I9300XXUGNJ2_I9300MSTGNJ1_MST.zip".

My question now, if my theory was wrong and i did somehow apply the right firmware at the first time, will it damage the phone if I applied a different firmware from other Service providers, and i mean this firmware that i am currently downloading?

PS: when the phone turned on the first time the battery had above 70% of charge, i'd like to know what caused the battery to go faulty all of a sudden even while having enough power!