The ROMLOADER of K200i requires a _shorter_ beacon interval than Pirelli (50), 10 seems to work:

$ host/osmocon/osmocon -p /dev/ttyUSB0 -m romload -i 10 target/firmware/board/se_j100/layer1.highram.bin

got 2 bytes from modem, data looks like: 3e 69  >i
Received ident ack from phone, sending parameter sequence
read_file(target/firmware/board/se_j100/layer1.highram.bin): file_size=62392, hdr_len=0, dnload_len=62395
Received parameter ack from phone, starting download
Finished, sent 62 blocks in total
Received branch ack, your code is running now!
fb_ssd1963_init: initializing LCD.


OsmocomBB Layer 1 (revision osmocon_v0.0.0-2590-g45cc12d6-modified)
======================================================================
Device ID code: 0xb496
Device Version code: 0x0000
ARM ID code: 0xfff3
cDSP ID code: 0x0128
Die ID code: e5141b20e5149b2d
======================================================================
REG_DPLL=0x2413
CNTL_ARM_CLK=0xf0a1
CNTL_CLK=0xff91
CNTL_RST=0xfff3
CNTL_ARM_DIV=0xfff9
======================================================================
Power up simcard:
Analyzing factory records sector at 0x3fc000
Bad record at 0x3fc000: rounded length is not aligned to 4
Assert DSP into Reset
Releasing DSP from Reset
Setting some dsp_api.ndb values
Setting API NDB parameters
DSP Download Status: 0x0001
DSP API Version: 0x0000 0x0000
Finishing download phase
DSP Download Status: 0x0002
DSP API Version: 0x3606 0x0000
LOST 7447!