@dpass,
ekincaid is right, very hard to brick an epic....still, make sure both your device + pc batteries are at least 50% (just in case), + you would be well advised to acquire a Blackberry microUSB cable as there is a high probability that your stock samsung mUSB will cause issues.....just sayin'
As for your install from stock FC09 Gingerbread to CM9_beta4 ICS Android 4.0.4, the following is a very brief how-to.....trust me, there are several other ways to do this but this is fairly generic:
[1] See links below, download necessary files to pc + place CM9_beta4 file into your downloads folder on microSD Card (this requires you to connect your device to pc, ensuring all necessary drivers are in place for your upcoming session w/ ODIN; .....also, give the ODIN thread a good read, then:
[*] BACKUP
[2] Power OFF device
[3] Device to Download Mode by pressing '1' + Power Button at same time
[4] Open ODIN on your pc, connect device to pc using mUSB cable, make sure ODIN detects your device as connected
[5] ODIN CWM5.0.2.7 Recovery (place 'CWM5.0.2.7' file in 'PDA' slot + select 'PDA' ONLY, do not select 'autoreboot' then click START.......await for ODIN to complete cycle (**DO NOT STOP this process, as this could very well brick your device**)
[6] when CWM install is complete > disconnect device from PC > pull battery from device for a few seconds, place battery back into slot
[7] then 3-finger boot to CWM Recovery ('down' button, 'camera' button + 'power' button simultaneously....then from CWM Recovery:
[9] flash CM9beta4 by (this will modify your CWM to 5.5.0.4 MTD + establish SU root)
[10] while still in CWM Recovery, after CM9_beta4 install completes........flash GApps20120429 file
[11] boot to system
[12] CM9_beta4: establish gmail settings + if you have apps stored on PlayStore......from PlayStore, install selected apps one-by-one (play store/menu/MyApps).............etcetera.
CWMv5.0.2.7 is here:
[RECOVERY] ClockworkMod 5.0.2.7 BML Officially supported by ROM Manager for Epic 4G - xda-developers
I got to part 6 and it said success on ODIN and when I pulled the battery to do the 3 button press, it doesnt do anything. The phone is completely dead now and nothing turns it on, what can I do?