[Android Q&A, Help & Troubleshooting] Nikiz:
I discovered 256 mysterious bytes in the end of the SM-G313HN boot images. Any idea what those are? Checksums? They are always located 1341 bytes after the end of secondary bootloader and the last 128 bytes seem to be the same between different images and regions. The phone boots without them, but a red exclamation mark appears in the top left corner of the screen while booting. I tried to compare different checksums to see if I could find a match, but I did not find any. (MD5, SHA1, SHA256, SHA512) Tested the kernel, secondary bootloader and some variables from the images.

Hex views:

Scandinavian boot.img:

Offset(d) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

05869568 CB C0 86 A6 EB A8 42 EE 63 27 D1 3E B0 EA D6 97 ËÀ†¦ë¨Bîc'Ñ>°êÖ—
05869584 71 BE AE 9C FA 74 47 7B 8B 0D 84 55 CC FA 1C D8 q¾®œútG{‹.„UÌú.Ø
05869600 AB D4 25 C6 93 8D 37 66 0A EB 3F 69 3C 94 2D 18 «Ô%Æ“.7f.ë?i<”-.
05869616 51 83 74 C0 BD 5B E7 A7 E4 F9 C4 A7 3B 03 C1 82 QƒtÀ½[ç§äùÄ§;.Á‚
05869632 3E 19 6C 9F 2B E0 A1 31 06 2B 34 90 9C A2 6D 88 >.lŸ+à¡1.+4.œ¢mˆ
05869648 53 AA C4 8D 2A BB DA 8D 5F 9B 51 1E E0 A1 00 4D SªÄ.*»Ú._›Q.à¡.M
05869664 43 C2 8C 28 6B 6A D6 DC D7 BB A7 81 0C 52 A0 16 CÂŒ(kjÖÜ×»§..R*.
05869680 59 83 3F 98 8F 0F 93 28 67 0E 64 63 44 F8 99 08 Yƒ?˜..“(g.dcDø™.
05869696 CF 44 1D 5B 0C 1D 30 8D 8C C8 02 D4 43 CB CE 5D ÏD.[..0.ŒÈ.ÔCËÎ]
05869712 D2 B8 04 12 6F 04 FF 35 3B 42 55 F3 EF 3E A8 F8 Ò¸..o.ÿ5;BUóï>¨ø
05869728 8E 1F AB 11 11 59 7C BB 38 E9 13 FB 0F 7D CD 84 Ž.«..Y|»8é.û.}Í„
05869744 1A FC D7 F9 65 DB 5D D0 6E B1 66 C4 19 1E 4E 5A .ü×ùeÛ]Ðn±fÄ..NZ
05869760 F5 00 0F D7 2B C3 27 38 D4 A0 DA 47 2B 0E 23 46 õ..×+Ã'8Ô*ÚG+.#F
05869776 2D 89 3F 64 72 36 16 DB 50 4E C3 E4 88 67 31 22 -‰?dr6.ÛPNÃäˆg1"
05869792 C6 C9 AF 05 34 92 1C E6 96 9F F8 8B 34 AD 33 DB ÆÉ¯.4’.æ–Ÿø‹4.3Û
05869808 5B 66 8A 9F 9D 21 53 C9 1A A4 70 C6 9B 0E AA E9 [fŠŸ.!SÉ.¤pÆ›.ªé

Scandinavian recovery.img:

Offset(d) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

07094272 56 68 66 CF 0D 52 6B 8C 2F F7 6C 0F 63 32 1B 9D VhfÏ.RkŒ/÷l.c2..
07094288 A6 46 B9 FC 07 E1 09 66 D3 CB 6D D4 BF A2 B0 81 ¦F¹ü.á.fÓËmÔ¿¢°.
07094304 24 6C 4D E3 97 79 6C 64 CE 27 31 AD 0F CD 5E 33 $lMã—yldÎ'1..Í^3
07094320 0A 0A 38 E8 58 27 5A 04 05 0B 48 99 00 5A A4 B8 ..8èX'Z...H™.Z¤¸
07094336 AC 53 11 E8 16 A9 55 81 A4 0F B6 F3 DF 21 F1 78 ¬S.è.©U.¤.¶óß!ñx
07094352 C5 E0 DF 38 7F ED B5 7B C5 0B D7 27 50 85 9E 26 Åàß8.íµ{Å.×'P…ž&
07094368 4C 45 8F FA 4C 74 38 F2 76 0F 47 73 8E A8 66 85 LE.úLt8òv.GsŽ¨f…
07094384 65 D3 B6 07 CA 8B E3 B8 D6 90 6D 36 D5 AB 1F D4 eÓ¶.Ê‹ã¸Ö.m6Õ«.Ô
07094400 CF 44 1D 5B 0C 1D 30 8D 8C C8 02 D4 43 CB CE 5D ÏD.[..0.ŒÈ.ÔCËÎ]
07094416 D2 B8 04 12 6F 04 FF 35 3B 42 55 F3 EF 3E A8 F8 Ò¸..o.ÿ5;BUóï>¨ø
07094432 8E 1F AB 11 11 59 7C BB 38 E9 13 FB 0F 7D CD 84 Ž.«..Y|»8é.û.}Í„
07094448 1A FC D7 F9 65 DB 5D D0 6E B1 66 C4 19 1E 4E 5A .ü×ùeÛ]Ðn±fÄ..NZ
07094464 F5 00 0F D7 2B C3 27 38 D4 A0 DA 47 2B 0E 23 46 õ..×+Ã'8Ô*ÚG+.#F
07094480 2D 89 3F 64 72 36 16 DB 50 4E C3 E4 88 67 31 22 -‰?dr6.ÛPNÃäˆg1"
07094496 C6 C9 AF 05 34 92 1C E6 96 9F F8 8B 34 AD 33 DB ÆÉ¯.4’.æ–Ÿø‹4.3Û
07094512 5B 66 8A 9F 9D 21 53 C9 1A A4 70 C6 9B 0E AA E9 [fŠŸ.!SÉ.¤pÆ›.ªé

German boot.img:

Offset(d) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

05865472 CA BE C5 61 D0 D3 C4 02 BE D7 99 02 63 DD 0D C3 Ê¾ÅaÐÓÄ.¾×™.cÝ.Ã
05865488 CB 89 28 40 B1 68 E5 54 F5 A3 98 42 47 79 88 4C Ë‰(@±håTõ£˜BGyˆL
05865504 1F 90 FC 48 5A 17 63 AB 1F D9 62 0A C4 70 31 6D ..üHZ.c«.Ùb.Äp1m
05865520 EF 07 F1 60 E2 CD 64 AC 15 92 41 3F 60 AB CC EA ï.ñ`âÍd¬.’A?`«Ìê
05865536 58 AF 08 ED DC 1E 25 04 94 19 FF 33 94 29 34 0A X¯.íÜ.%.”.ÿ3”)4.
05865552 A3 DF E6 8A 6D 6A 29 A5 0A 3A 55 10 12 52 45 8C £ßæŠmj)¥.:U..REŒ
05865568 36 C4 DB EE 21 F5 84 E1 31 83 C7 14 7C 92 1A 4F 6ÄÛî!õ„á1ƒÇ.|’.O
05865584 D2 99 FF 06 38 8B 8E 46 E4 EB DA 17 75 5E C4 65 Ò™ÿ.8‹ŽFäëÚ.u^Äe
05865600 CF 44 1D 5B 0C 1D 30 8D 8C C8 02 D4 43 CB CE 5D ÏD.[..0.ŒÈ.ÔCËÎ]
05865616 D2 B8 04 12 6F 04 FF 35 3B 42 55 F3 EF 3E A8 F8 Ò¸..o.ÿ5;BUóï>¨ø
05865632 8E 1F AB 11 11 59 7C BB 38 E9 13 FB 0F 7D CD 84 Ž.«..Y|»8é.û.}Í„
05865648 1A FC D7 F9 65 DB 5D D0 6E B1 66 C4 19 1E 4E 5A .ü×ùeÛ]Ðn±fÄ..NZ
05865664 F5 00 0F D7 2B C3 27 38 D4 A0 DA 47 2B 0E 23 46 õ..×+Ã'8Ô*ÚG+.#F
05865680 2D 89 3F 64 72 36 16 DB 50 4E C3 E4 88 67 31 22 -‰?dr6.ÛPNÃäˆg1"
05865696 C6 C9 AF 05 34 92 1C E6 96 9F F8 8B 34 AD 33 DB ÆÉ¯.4’.æ–Ÿø‹4.3Û
05865712 5B 66 8A 9F 9D 21 53 C9 1A A4 70 C6 9B 0E AA E9 [fŠŸ.!SÉ.¤pÆ›.ªé

German recovery.img:

Offset(d) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15

07090176 2A E6 B5 86 C2 95 C2 AA 6F C1 0A 8F 1A BD 19 3C *æµ†Â•ÂªoÁ...½.<
07090192 90 6F 6C 47 16 30 F4 F1 02 C7 20 1E 30 36 16 75 .olG.0ôñ.Ç .06.u
07090208 22 F3 DE 00 75 B3 57 F4 B1 36 2D 7E 32 30 CD 83 "óÞ.u³Wô±6-~20Íƒ
07090224 1F B2 57 DB 42 76 C4 7F 2A E5 62 74 0A 22 63 F5 .²WÛBvÄ.*åbt."cõ
07090240 A5 87 4E AC EF A9 CC D0 60 64 49 0B 29 D7 66 6C ¥‡N¬ï©ÌÐ`dI.)×fl
07090256 D1 C0 F4 36 18 7F DC C3 28 A5 B1 84 F9 C0 B1 B9 ÑÀô6..ÜÃ(¥±„ùÀ±¹
07090272 3D C1 F0 77 57 38 F3 23 12 F0 DF 43 F5 59 2D 52 =ÁðwW8ó#.ðßCõY-R
07090288 CF B4 75 69 70 22 E9 E6 6F 3E DE 78 60 2B A0 84 Ï´uip"éæo>Þx`+*„
07090304 CF 44 1D 5B 0C 1D 30 8D 8C C8 02 D4 43 CB CE 5D ÏD.[..0.ŒÈ.ÔCËÎ]
07090320 D2 B8 04 12 6F 04 FF 35 3B 42 55 F3 EF 3E A8 F8 Ò¸..o.ÿ5;BUóï>¨ø
07090336 8E 1F AB 11 11 59 7C BB 38 E9 13 FB 0F 7D CD 84 Ž.«..Y|»8é.û.}Í„
07090352 1A FC D7 F9 65 DB 5D D0 6E B1 66 C4 19 1E 4E 5A .ü×ùeÛ]Ðn±fÄ..NZ
07090368 F5 00 0F D7 2B C3 27 38 D4 A0 DA 47 2B 0E 23 46 õ..×+Ã'8Ô*ÚG+.#F
07090384 2D 89 3F 64 72 36 16 DB 50 4E C3 E4 88 67 31 22 -‰?dr6.ÛPNÃäˆg1"
07090400 C6 C9 AF 05 34 92 1C E6 96 9F F8 8B 34 AD 33 DB ÆÉ¯.4’.æ–Ÿø‹4.3Û
07090416 5B 66 8A 9F 9D 21 53 C9 1A A4 70 C6 9B 0E AA E9 [fŠŸ.!SÉ.¤pÆ›.ªé