do you happen to know which version of OS X is installed on the MacBook?
You are likely seeing automated messages offering remote service. You can safely ignore those.
Ok, try this and see if you get anywhere:
Power off your Mac.
Restart and, as soon as you hear the startup chime, press and hold the “OPTION” (or “Alt”) key at boot until the boot menu appears.
Then, select the “Recovery" volume.
(Alternative: If the above doesn’t work… Restart, hold COMMAND + R keys until you see the Apple logo and progress indicator. If neither of those work, try COMMAND + R + OPT.)
Wait for “OS X Utilities” menu to appear (DO NOT CHOOSE TO INSTALL)
Choose Disk Utility from the available options.
In Disk Utility, select your normal, bootable hard drive volume from the list in the sidebar (usually "Macintosh HD").
Then, Click “First Aid“ or "Repair Disk" (Next, click “Run”, if requested)
If it finds errors, repeat the process until it reports the drive is OK.
Once the process has completed, choose “Disk Utility” > “Quit Disk Utility” in the menu bar at the top of the display.
Then, restart your Mac and it should boot back into your normal Desktop.
Ok, good luck!
You were able to select the “Recovery" volume when booting, correct?
Ok, you won't if you used that combo rather than the Option key. It should get you to the same place eventually though.
Actually, if you used COMMAND + R + OPT(Alt) you should have activated Internet Recovery if your Mac supports it. You would see a slightly different network icon than the normal Apple Logo at boot if that worked. If not you should try OPTION (ALT) by itself or only COMMAND + R.... If none of those work after repeated tries then attempt the following;
1) Restart your Mac and hold the COMMAND and S keys together as soon as you hear the the start up chime. When the screen goes black and you start seeing text appear on screen, let go of the keys.
2) After a short period of time you will land at a command prompt (:/root#). At the command-line prompt, type:
and press Return.
- - -
“fsck” is a file system checker. It will run through a battery of tests, looking at different aspects of your file system.
When it's done, it will normally produce one of two messages
a) "The volume (name of your hard drive) appears to be OK
If it states the above, then your drive is fine and you can simply type "reboot" at the prompt and press Return to restart your Mac and boot back to the Desktop.
b) If fsck found any errors, it may have tried to correct them and will display this message: --FILE SYSTEM WAS MODIFIED--
If this message appears, repeat the fsck command you typed at the beginning:
and Press Return.
Keep repeating this until it reports your drive is OK.
If by some reason you need to do the above more than 5 times, this indicates a more serious issue. At the very least, the hard drive needs to be formatted and OS X should be re-installed.
However, assuming everything goes okay, type 'reboot' at the prompt and then press Return.
Once it has finished restarting you should be back at the desktop.