I'm sorry if you might find this answered somewhere else. But as far as my xda and google searching skills go, I've exhausted all options.
The rooted S3 (GT-I9300 on stock 4.3 ROM) I've been using was working perfectly fine until I decided to flash touch CWM. (Note: I had already installed the app through play store or blackmart). Now my phone is stuck in a weird download mode loop. It's weird because it's not the normal download mode that comes when you press the Volume Down+Home+Power buttons. It's almost the same, except that the other details on the top-left corner are not being displayed (such as Odin Mode, product name, custom binary download, custom binary ...).
However, I can still access the normal download mode using the above key combinations, only that that phone isn't recognized in Odin. Thus, I couldn't flash the stock rom using the same. Secondly, I can also access the recovery mode, but it's not CWM; instead, it's the stock android system recovery <3e>
Now, to make things worse, all my attempts at flashing custom recovery and stock rom through ADB were in vain. Every time I tried flashing a custom rom or recovery (using adb sideload filename), the phone gave me the following message (E:signature verification failed). I understand it's the case with stock recovery, but I just can't install custom recovery. And to top it all, my attempts at installing CWM and stock rom (I9300XWUGML4_I9300DDGML4_INU.zip) using the 'apply update from external storage' option (yes, I can access my extSDcard) yield me same results (E:signature verification failed).
So there you are, I tried adb; I tried Odin; I tried applying an update through external storage; I tried removing the battering and reinserting it (after almost four hours); I even tried factory resetting the handset, yet no positive results. My phone still goes to the weird download mode when rebooted. Please help. I don't want to bother everyone with stupid questions. I'm ready to do my research and help my case, but for now I'm at a roadblock. Your help would be much appreciated.
Was running on stock 4.3; no custom ROMs were installed; it was only rooted
Fri Dec 27 20:00:26 KST 2013