It stopped with the following at the end of `debug.log`:

---
2019-02-10T15:18:11Z UpdateTip: new best=00000000000000249597632a2fe08578cd1d2c0f620342ca91c3611786fe464f height=232591 version=0x00000002 log2_work=69.838772 tx=16550595 date='2013-04-22T14:31:02Z' progress=0.044502 cache=597.4MiB(5216340txo)
2019-02-10T15:18:12Z Error: Out of memory. Terminating.
---

I rebooted the raspi and it went straight to recovery mode... I will start from scratch again and do the hardware checks mentioned above.