[Galaxy S 4 Q&A, Help & Troubleshooting] om22:
I managed to trace it down. Seems like the L1 cache is somehow corrupted after the water damage.

Another log if someones interested:

[ 37.401977] L1 / TLB Error detected on CPU 2!
[ 37.402130] CESR = 0x00010002
[ 37.402374] CPU speed = 810000
[ 37.402526] MIDR = 0x511f06f0
[ 37.402679] D-cache data parity error
[ 37.402801] D-side CESYNR = 0x00002144
[ 37.402954] Kernel panic - not syncing: L1 nonrecoverable cache error detected
[ 37.403137] CPU0: stopping
[ 37.403289] [<c010b85c>] (unwind_backtrace+0x0/0xec) from [<c010abc8>] (handle_IPI+0x144/0x238)
[ 37.403381] [<c010abc8>] (handle_IPI+0x144/0x238) from [<c0100554>] (gic_handle_irq+0x138/0x164)
[ 37.403533] [<c0100554>] (gic_handle_irq+0x138/0x164) from [<c0105780>] (__irq_svc+0x40/0x74)
[ 37.403656] Exception stack(0xdeda5c20 to 0xdeda5c68)
[ 37.403747] 5c20: 00000001 ffffffff ffffffaa 00000001 c4998e40 c0f1a1c0 c0f1a1c8 00000003
[ 37.403869] 5c40: c0f17e40 00000000 00000001 03a81000 00000004 deda5c68 c017de58 c01d10f4
[ 37.404022] 5c60: 20000113 ffffffff
[ 37.404113] [<c0105780>] (__irq_svc+0x40/0x74) from [<c01d10f4>] (smp_call_function_many+0x26c/0x2a4)
[ 37.404266] [<c01d10f4>] (smp_call_function_many+0x26c/0x2a4) from [<c01d1174>] (smp_call_function+0x48/0x70)
[ 37.404388] [<c01d1174>] (smp_call_function+0x48/0x70) from [<c070d3b0>] (cpuidle_latency_notify+0x18/0x24)
[ 37.404541] [<c070d3b0>] (cpuidle_latency_notify+0x18/0x24) from [<c01a8bcc>] (notifier_call_chain+0x40/0x68)
[ 37.404693] [<c01a8bcc>] (notifier_call_chain+0x40/0x68) from [<c01a8e18>] (__blocking_notifier_call_chain+0x40/0x58)
[ 37.404846] [<c01a8e18>] (__blocking_notifier_call_chain+0x40/0x58) from [<c01a8e44>] (blocking_notifier_call_chain+0x14/0x1c)
[ 37.404998] [<c01a8e44>] (blocking_notifier_call_chain+0x14/0x1c) from [<c01bfdb8>] (pm_qos_update_target+0x118/0x130)
[ 37.405151] [<c01bfdb8>] (pm_qos_update_target+0x118/0x130) from [<c072c4b8>] (msmsdcc_enable+0x24/0x158)
[ 37.405242] [<c072c4b8>] (msmsdcc_enable+0x24/0x158) from [<c070fa9c>] (__mmc_claim_host+0x180/0x190)
[ 37.405395] [<c070fa9c>] (__mmc_claim_host+0x180/0x190) from [<c055a8c4>] (sdioh_buffer_tofrom_bus+0x50/0x118)
[ 37.405548] [<c055a8c4>] (sdioh_buffer_tofrom_bus+0x50/0x118) from [<c055ba14>] (sdioh_request_buffer+0x1e4/0x2ec)
[ 37.405700] [<c055ba14>] (sdioh_request_buffer+0x1e4/0x2ec) from [<c0559d58>] (bcmsdh_recv_buf+0xe4/0x110)
[ 37.405853] [<c0559d58>] (bcmsdh_recv_buf+0xe4/0x110) from [<c057e408>] (dhd_bcmsdh_recv_buf.constprop.8+0x68/0x84)
[ 37.406005] [<c057e408>] (dhd_bcmsdh_recv_buf.constprop.8+0x68/0x84) from [<c0581210>] (dhdsdio_readframes+0xbc8/0x183c)
[ 37.406158] [<c0581210>] (dhdsdio_readframes+0xbc8/0x183c) from [<c0585204>] (dhd_bus_dpc+0xa24/0x1230)
[ 37.406311] [<c0585204>] (dhd_bus_dpc+0xa24/0x1230) from [<c0576b60>] (dhd_dpc_thread+0x108/0x1a0)
[ 37.406402] [<c0576b60>] (dhd_dpc_thread+0x108/0x1a0) from [<c01a3040>] (kthread+0xb0/0xbc)
[ 37.406555] [<c01a3040>] (kthread+0xb0/0xbc) from [<c010673c>] (kernel_thread_exit+0x0/0x8)
[ 37.406677] CPU1: stopping
[ 37.406829] [<c010b85c>] (unwind_backtrace+0x0/0xec) from [<c010abc8>] (handle_IPI+0x144/0x238)
[ 37.406982] [<c010abc8>] (handle_IPI+0x144/0x238) from [<c0100554>] (gic_handle_irq+0x138/0x164)
[ 37.407135] [<c0100554>] (gic_handle_irq+0x138/0x164) from [<c010595c>] (__irq_usr+0x3c/0x60)
[ 37.407196] Exception stack(0xddfa5fb0 to 0xddfa5ff8)
[ 37.407348] 5fa0: 0000001b 12def1c0 00000002 12def000
[ 37.407501] 5fc0: b4284e00 b4283f00 00000014 133087b8 12c15b50 b4284e00 00008001 12e41f00
[ 37.407562] 5fe0: 71111850 acfcb010 b3ebc2d1 b41b125a 000d0030 ffffffff
[ 37.407714] CPU3: stopping
[ 37.407836] [<c010b85c>] (unwind_backtrace+0x0/0xec) from [<c010abc8>] (handle_IPI+0x144/0x238)
[ 37.407989] [<c010abc8>] (handle_IPI+0x144/0x238) from [<c0100554>] (gic_handle_irq+0x138/0x164)
[ 37.408142] [<c0100554>] (gic_handle_irq+0x138/0x164) from [<c010595c>] (__irq_usr+0x3c/0x60)
[ 37.408294] Exception stack(0xdcd71fb0 to 0xdcd71ff8)
[ 37.408386] 1fa0: 00000000 9c747600 00000034 00000034
[ 37.408538] 1fc0: a7b3bc80 a7b3bc80 b42d5140 00000034 9ec9b5b7 9c747600 a7b3bc98 97f33e30
[ 37.408599] 1fe0: 00001002 97f33d30 b409aafb b3ec69b0 200f0030 ffffffff
[ 37.810028] Rebooting in 5 seconds..
[ 42.825500] Going down for restart now
[ 42.825927] msm_restart : clear reset flag

I don't think there is hope for this board anymore :silly: