Lost boot ability to OSX and Windows 10

For the record please post the output of the following OSX Terminal command.

sudo gpt -vv -r show /dev/disk0

No worries about formatting. 😉. Looks clean. Please test switching between the two OSes and visibility to the Shared partition after the following steps. You will not be able to see the OSX partition from the Windows side, because it will be combined with Recovery HD.

This is not a standard Hybrid MBR. Standard MBR contains GPT 2,3,4 but we are using GPT3,4,5.

Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers. Please see thesample Q&A as an example. These steps can be repeated if you make a mistake before you get to Step 12, otherwise start from Step 1 for these steps. Step 6 has numbers which are typed with a space between the numbers.

1. Sudo gdisk /dev/rdisk0
2. P (Print list of parts)
3. R (Recover)
4. O (print current Hybrid MBR)
5. H (chooses Hybrid)
6. Partitions numbers to be hybridized: 3 4 5
7. Y (Good for GRUB question)
8. N (part 2 boot flag)
9. N (part 3 boot flag)
10. Y (part 4 boot flag make NTFS bootable partition)
11. O (print current Hybrid MBR)
12. W (Write the new MBR)
13. Y (Yes! write the new MBR)
14. Reboot

Here is sample Q&A for this section. Please notice the Press Enter/Return.

Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y

Creating entry for GPT partition #3 (MBR partition #2)

Enter an MBR hex code (default AF): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #4 (MBR partition #3)

Enter an MBR hex code (default AB): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #5 (MBR partition #4)

Enter an MBR hex code (default 07): Press Enter/Return

Set the bootable flag? (Y/N): Y

Thank you for your service to whichever country's Armed Forces you are serving. Post back when you have time. 😉. One suggestion is to switch to OSX if possible, since it has richer tools to go further.

We fixed your OSX booting issue using Widows 10 Gdisk commands. You should be able to switch between OSX and Windows using Boot Camp: Set the default operating system or using the Alt/Option key during power up/down cycle.

Your W10 should also boot normally now. Please test. If you see any issues with W10 or missing W10 drivers, please post back.

From the MBR perspective, the Windows that is currently booting is GPT#5 which is 279GiB. Is the 92GiB partition the Windows 10 partition?

Can you check the available options in System Preferences -> Startup Disk?

If you select the Bootcamp Windows, which version of Windows do you get?

1. What i steh year/model of your Mac?

2. Can you post the output of the following Terminal commands?

sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C

sudo dd if=/dev/rdisk0s5 count=1 2>/dev/null | hexdump -C

The "sudo" commands will prompt for your password, and it will not be echoed back. You may also see a warning about improper use of "sudo" and potential data loss due to "abuse" of the command.