To get it powered up try removing the battery for 30 secs then see if it'll boot. Failing that, boot into recovery, wipe dalvik and cache then reboot.
It'll take longer to boot after wiping the cache so be patient.
Once you're booted you can get the sdcard as follows. I had the same issue and it worked for me.
Check your hboot by booting into bootloader...
Note if you're on 1.25 or 1.28
You will need to edit the vold.fstab file.
Using ESFileManager or RootExplorer go to /system/etc and open vold.fstab up in Text editor and find this line
dev_mount sdcard /mnt/sdcard 34 /devices/platform/msm_sdcc.2/mmc_host/mmc0
For 1.25 hboot, where it says 34 you will need to change that to 33, save the changes and reboot the phone..
For 1.28 hboot, where it says 33 you will need to change that to 34, save the changes and reboot the phone.
I'll test it if my device is working again
I talked in a chat with some guys and they told me my device is bricked and I have to Jtag it..
So is there the only way to save my device or can I unbrick it with Linux like some one did it with an Htc sensation?