https://duckduckgo.com/?q=boot+usb+lenovo+g50-70
According to http://support.lenovo.com/us/en/documents/ht076906 , the user is instructed to perform the following steps in order to access the boot menu:
To access the Boot Menu:
1. Open the Charm Bar by pressing Windows Key-C
2. Click on Settings
3. Click on Change PC Settings
4. Click on General
5. Scroll to the bottom and click on Advanced Startup -> Restart Now
6. Click on Use A Device
7. Click on Boot Menu
However, there is no "General" button or tab [Step 4]. Rebooting whilst mashing ESC, F2, F8, F10, or F12 did not lead to BIOS configuration or the boot menu - in fact, mashing F12 led to a notice that this feature was DISABLED. Time to call in HRT.
So...
A little more searching lead to:
http://superuser.com/questions/852235/how-to-install-ubuntu-14-10-on-a-new-lenovo-ideapad-g50-70/
The instructions contained therein were incomplete and/or incorrect.
After some time exploring every single last option derivative of Lenovo's steps 1-3, victory was finally wrested from the bony graspings of Microlenosoftvo.
Giving back to the community is considered an obligation - and a happy one. To that end, here follow the precise steps followed that successfully eliminated the hostage situation on a Lenovo G50-70 that was purchased with real monies dollars shekels bills. May bitrot claim what remains of Microsoft's soulless corpse.
- - - - -
How to bypass UEFI Hardware Hostage Infection on a Lenovo G50-70 Thereby Allowing the Owner to Install Whichever Operating System SHe Chooses
Needed tools: (1) Lenovo G50-70 [or probably any of many other similar models, YMMV], and (1) USB Stick to Which the ISO of One's Preferred Operating System Has Already Been Written.
00. Main Screen Turn On!
01. Open the Charm Bar by pressing Windows Key-C
02. Click on Settings:
03. Click on Change PC Settings:
04. There is no "General" setting. Here we deviate from the Lenovo Lie: Click on "Update and Recovery":
05: Advanced Startup / Restart Now:
## System will restart.
06: Click "Troubleshoot":
07: Click "Advanced Options":
08: Click "UEFI Firmware Settings":
09: Click "Restart":
## System will restart. Again.
##: BIOS now accessed. Victory in sight:
10: right-arrow over to "Boot":
11: "Boot Mode / UEFI" is highlighted. Press "Enter", down-arrow to change to "Legacy Support"; press "Enter":
12: down-arrow to highlight "Boot Priority / UEFI First"; press "Enter"; down-arrow to select "Legacy First"; press "Enter":
13a: down-arrow to highlight "USB Boot"; make sure it is "Enabled":
13b: Insert your Joy Stick, by which it is meant "Stick of Joy", or, USB Stick to Which the ISO of One's Preferred Operating System Has Already Been Written.
14: right-arrow to "Exit"; select "Exit Saving Changes"; press "Enter":
## System will restartings.
15: WINNING!:
**NOTE** Yes, this is the 32-bit version of Mint. This is *not* the recommended installation for this machine - it was just the nearest USB stick with an ISO, since step 13b was performed just a little too long after step 14. For anyone who is interested, Linux Mint 64-bit works *flawlessly* on this machine.
And? This property owner is very displeased with both Lenovo & Microsoft for their collusion & complicity in infecting *MY* hardware with UEFI hostageware. I purchased this hardware with my monies, and that means it is unacceptable to make it so difficult to do as I please with it.
Specifically, boot from USB and/or boot from CD were:
1) disabled by default, and
2) not easily re-enabled, and
3) the boot menu, typically accessed on this machine via pressing "F12" at power-up is _not_ accessible without going through the "gateway" of Windows 8. To repeat: critical system components were deliberately crippled by the manufacturer [Lenovo] and made to work only with certain [Microsoft] ransomware.
And in presponse to those who may choose to argue that results were in fact attainable, therefore no impediment was imposed, therefore Microlenosoftvo are not dirty; I say: Foul. There is no legitimate reason to bury access to critical system functions such as BIOS and the boot menu. It is _not_ a "security" feature beyond securing monopoly. Period. This is attrition. Rewind ten years and BIOS/BootMenu were easily available. Today UEFI/W8 have distanced that access very significantly. Promise, the goal is to remove BIOS access completely to OS control, exclusive to MSWin.