Kernel file not loading correctly in MASM

Just making a simple OS as a beginner for my assembly project. I have this very simple bootloader which prints a character B and reads the second sector (kernel) from drive and loads it at 10000h memory address

.model tiny
ORG 7C00h
.code
start:
    cli
    mov ax, 07B0h
    mov ss, ax
    mov sp, 00FFh
    sti
    mov ax, cs
    mov ds, ax

    mov ah, 0Eh 
    mov al, 'B' 
    int 10h   

    ; Reading kernel
    mov ah, 02h
    mov al, 1   
    mov ch, 0       ; cylinder
    mov cl, 2  
    mov dh, 0       ; head
    mov dl, 0 
    mov bx, 0
    mov ax, 1000h
    mov es, ax
    int 13h

    jc disk_error
    
    mov ah, 0Eh
    mov al, 'J'
    int 10h 

    jmp es:[bx]

disk_error:
    mov ah, 0Eh
    mov al, 'E'
    int 10h

db 510-($-start) dup(0)
dw 0AA55h
end start

I'm using qemu to test, it is printing B and J but not K or anything I try to print or do in kernel:

.model tiny
org 0
.code
start:
    cli
    mov ax, 07B0h
    mov ss, ax
    mov sp, 00FFh
    sti
    mov ax, cs
    mov ds, ax

    mov ah, 0Eh 
    mov al, 'K' 
    mov bh, 0    
    mov bl, 7 
    int 10h 

    jmp $

db 512 - ($ - start) dup(0)
end start

I can't find any resource which uses MASM to develop an OS all resources are on NASM which is not part of our course. Bootloader seems to work fine but can't seem to figure out if jmp is not working or if something's wrong in kernel file.