I recently installed a dual boot with my windows 7 to try it out. After checking it out i shut it down so i could use windows for school. Now my pc won't turn on at all. Can't even get into bios. After hitting power its black and flicks off after like 7 seconds. I need to use windows!!! I installed both on c drive and didn't set a default. Not even ubuntu starts so now my laptops useless. Im on my phone now. Please help.
Sounds like it's a hardware problem, rather anything related to software. Try to unplug power adapter and remove laptop battery, connect it back after couple of seconds, and try to boot.
There are some machines on which Linux will freeze, after a restart or a shutdown command is issued, right at the very end of the process forcing you to do a hard reset – press the reset/power button the system or plug the cord which is not good. In this post we will see how you can resolve almost 99% of freeze/hang that occurs during shutdown or reboot.
Why this happens
There are many reasons why this happens – some times it is an BIOS issue or sometimes it’s just that your system has a different kind of hardware setup, for example no keyboard controller, and Linux (the kernel) does not understand how to tackle that situation. Most of the time if it is a BIOS issue it is not very easy to ask your system vendor to give you an immediate BIOS fix that will take care of the issue and hence you have to rely on some kernel parameters that you need to pass to fix the hang/freeze issue.
Let’s say you bought a new machine and you notice that your Linux distribution hangs at the very end of the reboot/shutdown process, upon giving any of the following commands:
In order to fix the issue, you should try one-by-one passing the following parameter to the kernel, in the form of
As per my experience, one of the parameters (with the asterisk above) should be able to resolve your hang (or freeze) issue 90% of the time:
Once your system boots you can verify whether the parameter was correctly passed or not by issuing the following command:
You can find the list of all the above parameters in the reboot.c file in the Linux kernel source.
By default, the Linux kernel uses the reboot=kbd method i.e. it tries to look for a keyboard controller and issue a reset/shutdown command to it. But there are some systems like some of the Intel Atom processor based machines that don’t have a keyboard controller and the above fixes are required. If you read the reboot.c file carefully there are some major main stream machines from Dell, Sony, HP, etc. that require the above “reboot=” fix. I guess sometime it is easier to fix the issue by using the kernel parameter rather than fixing in the BIOS.
Also you can also use the first letter (as denoted in the “” brackets) of each of the parameter:
and you can pass multiple parameter at the same time and Linux kernel will try in order specified:
Credit goes to Kushal Koolwal.