If you have a V1 player (denoted by just having E2xx not ExxV2) then you can try to place the player into recovery mode and reflash the firmware. To do this, follow these steps:
1: With the player off (press and hold the power button for 30 seconds if you're unsure) activate the hold switch by sliding the switch at the top of the player towards the headphone jack so that you see orange.
2: Press and hold the record button on the left hand side and connect to the computer (KEEP RECORD HELD DOWN)
3: Watch the screen of the player, it should be DOS looking writing on it, once you see Welcome to Recovery Mode on the player you may let go of the record button
4: Open your My Computer Icon and you should see a folder/icon that says "16MB Format". Open this and you should only see one file at the moment, it will say Version.txt
5: Now you'll need to download the manual firmware update. (Ensure that your player doesn't have a "R" at the end of it) as that would need a different firmware. *NOTE: There is a difference between E200 and E200R and E200V2.
If its an E200, click here
If its an E200R, click here

 Download the firmware and unzip/extract the files. Once the files are extracted, copy them and then paste them into the 16MB Format folder where the Version.txt is.

Once the files have been pasted in this folder, disconnect the player and watch its screen. It should say something along the lines of "Reading main image, writing main image, time taken...."

It'll restart and give you a keylock error. Remove the holdswich and try to boot up.

If you don't see any txt on the screen of the player, try again as it may not have been done correctly.

If it does the update but still fails to boot, you may want to remove the battery, press and hold the power button for 60seconds then reseat the battery and try to power it on. If that fails, if the player is less than 1year old, then just call SanDisk and they should be able to create a RMA. If it's older than that, let me know and we can try one last thing.. it'll require pictures (by me) 

It will probably be an RMA then, as the techies are gonna have you do the above

Try removing the battery. Press and hold power (without the battery) for 30 seconds. Once done, put the battery back in, and try to charge it. If that doesn't work, you may need to place the device in recovery mode and create the Sansa.fmt file.. I know i made a walkthrough somewhere... I'll post a follow-up when i find it