Emberrasing basic question: How to start my Pi 3 B (with retropie) after shutting it down...

Question

As you already see in the title i have a question so basic, it's embarrassing. After i booted retropie on my first brand new Pi, i installed some roms with a USB stick, played a couple of minutes mario and then shut the pi down through the option in the main menu. After this i turned the power source off (5V 2A). And here is my problem: I can't get it back on. When i connect the power source again it starts blinking red and green, but my monitor doesn't do anything (and yes i checked if it is on C: ). Please be kind as i have no experience at all with raspberry pi's! Thank you in advance, Brabbelback! (Attached: a picture of my test-setup for my PIK3A table. The pi is connected with the controller (which works well) and a keyboard.) 
 Attachments:

michaelwylie · Accepted Answer

I've seen this before. It's power related. You can do a google search for just retropi won't boot after power down and you will see other people with the same problem. Hopefully the new power supply allows the system to shutdown correctly without corrupting the SD card.

brabbelback · Answer

The SD card was corrupted because the power supply was too low!

michaelwylie · Answer

Reinstall the image on the card (format first) and try to boot it. I suspect there is an issue corrupting the SD card.

e14 Contributor · Answer

It sounds silly but disconnect the power, remove the sdcard then put it back in and apply power again. Give it a try, if it works then you may have the problem re-occur. It happens with somd brands of sdcard but not others. If it doesnt work try a re-install like michael suggests above

balearicdynamics · Answer

Don't worry are other the thing that can be embarassing... Just a first suggestion: Pi3 expect a power supply 2.5A and not 2A Maybe that while installing and setting up you have added the parts one by one and the power was sufficient. Now after the entire setup has been done with only 2A Pi may have serious problems to restart. Maybe not, but in my opinion this is the first thing to consider: try if possible to remove - also temporary while booting - something not essential, like the USB stick if you have left it inside and see if the system start again. If not, leave only the monitor connected and try booting adding progressively all the connections and see if something generate the boot stop. If possible also describe what you see while booting: after powering red led should be on then green led will start blinking while boot proceed, if I am not wrong. Enrico

beacon_dave · Answer

Perhaps take a look at this trouble-shooting Wiki R-Pi Troubleshooting - eLinux.org As you can see, the flashing red power LED usually suggests power related issues. The new 2.5A PSU may resolve this.