Lenovo z50-70 suddenly shuts down, won't turn on

Greetings, Suzanne:

Before things get messy, try different combinations of what you've already done, e.g. powering up the machine using the AC cord only (without the battery installed). Also, make sure to touch a bare piece of metal, like a kitchen faucet, regularly to remove static from your fingers.

If your machine is still under warranty (under 2 years old), you should contact Lenovo. Go to lenovo.com and open the chat feature. They may be able to help you right away, or at least tell you how to use the warranty.

If it isn't, or if you're willing to risk voiding the warranty, you can unscrew the panels and:

a) remove and reinsert the RAM module(s), and/or
b) locate the CMOS battery and remove it for a few hours and then reinsert it.

Can you remember what you were doing immediately prior to the break-down? My initial reaction was RAM overload, which might be remedied by reinserting the module(s). Your comment about the machine turning on briefly with the Windows button does sound like a RAM problem.

Alternatively, it might be a graphics issue, which is often solved only by doing a factory reset.

Be advised that choosing b) will wipe your HDD and you will lose everything. Upon restart, you should see a Lenovo recovery screen prompting you to reinstall the OS.

Best of luck,
GreyCatz.