SD cards are the same brand: Qlive 32GB 80MB/S read 20MB/S write
What is connected to my R3:
- Power supply
- RJ45 to WAN port
- USB-UART (RS232 TTL) CH340G via USB to my laptop
Without spending money, I would disconnect RJ-45 and USB-UART (maybe that’s nonsense).
Boot from SD crad and look what happend? Normal boot? After that, connect USB-UART and try to see openwrt logo?
If that not helps:
→ “professional” delate SD card download Openwrt image again and write it on SD card … and so on …
These I am repeating for the last 2 days xD I have no idea how many times I have done it but at least 50.
But maybe there is sth wrong with my clearing sd-card method. What i do to clear my sd card:
fdisk /dev/sdb
Welcome to fdisk (util-linux 2.40.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
The backup GPT table is not on the end of the device. This problem will be corrected by write.
A hybrid GPT was detected. You have to sync the hybrid MBR manually (expert command 'M').
Command (m for help):
Command (m for help): d
Partition number (1-7, default 7):
Partition 7 has been deleted.
Command (m for help): d
Partition number (1-6, default 6):
Partition 6 has been deleted.
Command (m for help): d
Partition number (1-5, default 5):
Partition 5 has been deleted.
Command (m for help): d
Partition number (1-4, default 4):
Partition 4 has been deleted.
Command (m for help): d
Partition number (1-3, default 3):
Partition 3 has been deleted.
Command (m for help): d
Partition number (1,2, default 2):
Partition 2 has been deleted.
Command (m for help): d
Selected partition 1
Partition 1 has been deleted.
Command (m for help): n
Partition number (1-128, default 1):
First sector (34-62410718, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-62410718, default 62408703):
Created a new partition 1 of type 'Linux filesystem' and of size 29,8 GiB.
Command (m for help): p
Disk /dev/sdb: 29,76 GiB, 31954305024 bytes, 62410752 sectors
Disk model: SD/MMC
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 5452574F-2211-4433-5566-778899AABB00
Device Start End Sectors Size Type
/dev/sdb1 2048 62408703 62406656 29,8G Linux filesystem
Command (m for help): w
The device contains hybrid MBR -- writing GPT only.
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
and then i write an image like that:
sudo dd if=openwrt-23.05.5-mediatek-filogic-bananapi_bpi-r3-sdcard.img of=/dev/sdb
I remember a guy, who said he has to writhe the whole space with ones. In the history I had some problems with USB-Devices for booting on a pc … .
I have not so much experiece → I thing it is the SD card. We had some usere at this forum who reported that …
Best is, to borrow one from a friend of yours and check it out! I would prefer Samsung.
I can give it a try, but I wonder if maybe there are some min write and read speed recommendations? Do you have any idea or nope ?
No, i had never problems with that. Boot from SD Card is usually very easy.
The most people who asked for help, fall over the “step by step sequence” to write the data on EMMC.
Thanks for your time. 
Tomorrow I will try again, maybe someone will post some useful advices
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Good luck. Do not give up! R3 is worth the work 
Then you do not need it.