I've done as suggested, and now my device won't boot:
[ 3.185127] UBI: auto-attach mtd6
[ 3.188583] ubi0: attaching mtd6
[ 3.613904] __nand_correct_data: uncorrectable ECC error
[ 3.619442] ubi0 warning: 0x802a3910: error -77 (ECC error) while reading 64 bytes from PEB 265:0, read only 64 bytes, retry
[ 3.631687] __nand_correct_data: uncorrectable ECC error
[ 3.637182] ubi0 warning: 0x802a3910: error -77 (ECC error) while reading 64 bytes from PEB 265:0, read only 64 bytes, retry
[ 3.649431] __nand_correct_data: uncorrectable ECC error
[ 3.654933] ubi0 warning: 0x802a3910: error -77 (ECC error) while reading 64 bytes from PEB 265:0, read only 64 bytes, retry
[ 3.667179] __nand_correct_data: uncorrectable ECC error
[ 3.672699] ubi0 error: 0x802a3930: error -77 (ECC error) while reading 64 bytes from PEB 265:0, read 64 bytes
[ 3.683048] CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.184 #0
[ 3.689078] Stack : 804c76a2 00000032 00000000 00000001 00000000 00000000 00000000 00000000
[ 3.697771] 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 3.706471] 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 3.715172] 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 3.723871] 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 3.732572] …
[ 3.735108] Call Trace:[ 3.737460] [<8006b0cc>] 0x8006b0cc
[ 3.741076] [<8006b0cc>] 0x8006b0cc
[ 3.744680] [<802a3938>] 0x802a3938
[ 3.748287] [<802a3c9c>] 0x802a3c9c
[ 3.751899] [<802a361c>] 0x802a361c
[ 3.755506] [<802a8ba8>] 0x802a8ba8
[ 3.759123] [<8029e00c>] 0x8029e00c
[ 3.762726] [<802a9dcc>] 0x802a9dcc
[ 3.766330] [<8029e020>] 0x8029e020
[ 3.769946] [<800a978c>] 0x800a978c
[ 3.773553] [<8049c428>] 0x8049c428
[ 3.777153] [<8049c0a4>] 0x8049c0a4
[ 3.780768] [<80483230>] 0x80483230
[ 3.784374] [<800609f4>] 0x800609f4
[ 3.787976] [<80270008>] 0x80270008
[ 3.791593] [<80097e6c>] 0x80097e6c
[ 3.795198] [<800a3b18>] 0x800a3b18
[ 3.798802] [<80483d10>] 0x80483d10
[ 3.802416] [<80483230>] 0x80483230
[ 3.806020] [<803e0b18>] 0x803e0b18
[ 3.809638] [<803e0b28>] 0x803e0b28
[ 3.813243] [<803e0b18>] 0x803e0b18
[ 3.816844] [<80066278>] 0x80066278
[ 3.820465]
[ 3.822954] __nand_correct_data: uncorrectable ECC error
[ 3.828451] ubi0 warning: 0x802a3910: error -77 (ECC error) while reading 64 bytes from PEB 265:512, read only 64 bytes, retry
[ 3.841183] __nand_correct_data: uncorrectable ECC error
[ 3.846684] ubi0 warning: 0x802a3910: error -77 (ECC error) while reading 64 bytes from PEB 265:512, read only 64 bytes, retry
[ 3.870261] __nand_correct_data: uncorrectable ECC error
[ 3.875762] ubi0 warning: 0x802a3910: error -77 (ECC error) while reading 64 bytes from PEB 265:512, read only 64 bytes, retry
[ 3.900409] __nand_correct_data: uncorrectable ECC error
[ 3.905911] ubi0 error: 0x802a3930: error -77 (ECC error) while reading 64 bytes from PEB 265:512, read 64 bytes
[ 3.916444] CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.184 #0
Any suggestions?