[Galaxy S 5 Q&A, Help & Troubleshooting] ekns:
CM Installation Problems

I posted this last night on the CM forums and have had one responder but thought this might reach a wider audience. I'm copying and pasting the OP and I'll try to include as much info as possible.

Hi,

I'm fairly new to flashing etc. New as in this was the first time I tried it. I'm fairly tech savvy, I just haven't flashed a custom rom before.

I followed all the instructions on the CM wiki for the S5 (AU).

Long story short, every step in those instructions worked perfectly once I accounted for my own errors or misunderstandings. Flashed the TWRP recovery just fine. There were problems with ADB not working when the phone was in recovery mode (discovered it's something to do with win 8 and above) so I just rebooted into stock rom (where ADB worked) and used adb push to copy the files to sdcard. Everything went swimmingly until the actual CM installation. I followed the instructions and did the factory reset, went to install and the installation took something like 10 mins before I started to wonder how long it was meant to take. Little bit of googling got me more worried, after about 20 I pulled the battery, back into recovery and went into Wipe again. Cleared Dalvik, cache, system all manually and then did the factory reset option on top of that just to be thorough. Installation is still taking forever. It's currently been around 20 minutes. Some posts I've read say rooting is required but that installation article specifically says rooting is neither required nor recommended. I've no idea where to turn now. I can't use ADB to copy a stock firmware back on as it doesn't work in recovery mode, nor can I try the klte or kltedev versions (don't think they're meant for this model anyway). It's just stuck on "flashing file 1 of 1" - the last thing in the log is "Patching system image unconditionally..." I'm running windows 10, not that that should make any difference.

Any help would be hugely appreciated.

Update: After about 40 mins I pulled battery again and thought I'd try booting normally and seeing what it does. Just sits at "Samsung Galaxy S5" splash screen.

TL;DR/Extra info:

Galaxy S5 G900I (AU) Vodafone

Was running Lollipop 5.0 as per Vodafone OTA update

Using instructions on the CM wiki page for the GS5 (AU) I flashed TWRP using Heimdall with no errors. ADB would not work in download/recovery (couldn't see device) so booted phone into stock ROM and used ADB push to copy the CM file to sdcard root. Note: I don't have an sd card, it's internal storage. Rebooted into recovery, tried to flash CM, it sat on installation screen for about 20 mins. Tried 3 times, leaving it for 40 mins, still nothing. Stock OS has been wiped so I can't get back into that, and because ADB doesn't work I can't reflash recovery from scratch, can't copy a new download of CM on, can't copy the stock ROM to flash. ADB Sideload just tries to run and fails. Currently trying to get ADB working. Running Win 10, device stopped showing up in device manager or Zadig at this point. Restarted PC, ran Zadig again, it saw device, reinstalled driver, now shows up in device manager under USB Devices as MSM8960 (so not under Portable Devices as it once did). Note: the safely remove icon in system tray showed "Galaxy S5 (Phone name)" before I ran Zadig again, now it shows MSM8960.

Help :(