[Galaxy Note 10.1 (2014 Edition) Q&A, Help & Troubl] oldcpu:
For the record (in case anyone with same Tablet is curious) this is what I did to install TWRP and LineageOS on my Samsung Galaxy 10.1 (2014) SM_P605 (Snapdragon 800) tablet (after obtain helping on this forum not to worry about OEM mode).

I used openSUSE LEAP-15.2 GNU/Linux to flash TWRP-3.2.3-0 on to the tablet. Once TWRP was installed I booted the Tablet to TWRP and used TWRP to flash lineage-14.1-20210320-UNOFFICIAL-lt03lte and open_gapps-arm-7.1-stock-20220122.

Details:

On openSUSE-LEAP-15.2 GNU/Linux I installed android-tools ( https://software.opensuse.org/package/android-tools ) and heimdall ( https://software.opensuse.org/package/heimdall ).

I pre-installed in the Samsung tablet storage (root location) the files: lineage-14.1-20210320-UNOFFICIAL-lt03lte.zip and open_gapps-arm-7.1-stock-20220122.zip . In hindsight I should also have pre-installed a TWRP.zip version, but I failed to do so.

I spent some time checking my various USB cables to pick the best one wrt reliability for copying data/charging devices, and I used a USB-2 port, and not a USB-3 port for connecting my GNU/Linux PC to the Tablet. I previously read that could make the difference in ensuring a successful effort.

I note this was the previous Tablet state when booting to ODIN mode:

ODIN MODE
PRODUCT NAME: SM-P605
CURRENT BINARY: CUSTOM
SYSTEM STATUS: CUSTOM
KNOX WARRANTY VOID: 0X0
QUALCOMM SECUREBOOT: ENBALE (CSB)
RP SWREV: S2, T2, R2, A2, P2
SECURE DOWNLOAD : ENABLE
UDC START

As near as I could determine, there was no custom bootloader (boot loader may even have been locked ?? ) and the tablet was not rooted.

With the Tablet running I plugged the USB cable into the Tablet. I noted a popup in KDE desktop on my GNU/Linux detecting the Tablet.

I prepositioned in my GNU/Linux PC, in a directory (in which I was to open a bash shell) the TWRP file: twrp-3.2.3-0-lt03lte_20180923.img

On my GNU/Linux PC I opened a bash shell and I typed:

sudo adb reboot bootloader

That rebooted the Tablet to "Download" (I think also refered to as "FastBoot mode" ). There was no KDE popup this time. However typing :

sudo heimdall detect

gave me an indication that the Tablet was detected by heimdall.

In that same bash shell I then typed:

sudo heimdall print-pit

I scolled through the resultant "pit" output and I found an entry with "RECOVERY" and "recovey.img" (Entry-14). ie

--- Entry #14 ---
Binary Type: 0 (AP)
Device Type: 2 (MMC)
Identifier: 15
Attributes: 5 (Read/Write)
Update Attributes: 1 (FOTA)
Partition Block Size/Offset: 268288
Partition Block Count: 26624
File Offset (Obsolete): 0
File Size (Obsolete): 0
Partition Name: RECOVERY
Flash Filename: recovery.img
FOTA Filename:

Seeing 'Recovery' in 'Entry-14', in that same bash shell I then typed:

sudo heimdall flash --14 twrp-3.2.3-0-lt03lte_20180923.img --no-reboot

The Tablet seemed to hang there with a blue line indicating flashing ? I waited a few minutes and there was no further indication on the Tablet display. I thought the flash failed, so I held down the power off to shut down and restart the tablet.

The Tablet to my surprise, rebooted to TWRP. I don't know precisely what caused that (as I described what I did above with a power-off to restart), but I decided to immediately take advantage of the tablet booting to TWRP.

At that point I followed the regular instructions on the Internet for flashing LineageOS on the Tablet from TWRP ... ie using TWRP, to WIPE data, clear CACHE, and flashed lineage-14.1-20210320-UNOFFICIAL-lt03lte.zip with NO reboot specified. I cleared CACHE again (possibly not needed) and then flashed open_gapps-arm-7.1-stock-20220122.zip . Unfortunately I did not have a "TWRP.ZIP" prepositioned on the Tablet, so I was not able to flash that next. I suspect this was a mistake on my part, and if I wish to update again, I will again need to go through the above to put TWRP on the table.

I then rebooted the tablet (disconnecting from PC) and it booted to LineagOS-14.1 (with android-7.1.2).

I am pleased the Tablet camera functions with v.14.1.

I believe with the current flash that TWRP is no longer installed. I have not checked the Tablet's updated PIT output.

I do note the ODIN mode on the table is almost the same, except for Knox warranty void entry which reads "KNOX WARRANTY VOID: 0X1 (1)"

Hopefully the above may help someone - although no guarantees as it could brick your device for all I know. Fortunately it did not brick mine.

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Prior to the above, what did not work for me with stock Samsung Android 5.1.1:

- fastboot, that came with Android tools, would not work for me when the Tablet was in 'Download'/'ODIN mode'. That is why I switched to using heimdall.

- I tried to root the Tablet prior to installation with Magisk (downloading from the web) but that rooting failed. I tried installing (from Google playstore) TWRP on the Tablet, but it kept saying no root permissions and would not give me flash capable options. I was unable to install Magisk with TWRP (from Google playstore) as I had no root permissions on the tablet. I did not want to use other 3rd party root apps as I was concerned about possible maleware. That is why I ended up using a PC to flash TWRP.

- I tried to flash TWRP with

sudo heimdall flash --RECOVERY twrp-3.2.3-0-lt03lte_20180923.img

and also with

sudo heimdall flash --RECOVERY twrp-3.2.3-0-lt03lte_20180923.img --no-reboot

and neither worked.

The first gave an indication that the PIT file was successfully downloaded and that RECOVERY upload was successful, but in fact if failed, as the Tablet would not go to TWRP during a reboot.

In the case of the second heimdall, the tablet just hung for over 10 minutes with a blue bar, so I simply restarted the tablet.

Only by specifying the "14" (from Entry-14) was I able to get heimdall to work for me (having previously determined the RECOVERY was in entry-14).